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#include<iostream> |
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#include<cstdio> |
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#include<algorithm> |
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#include<climits> |
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#include<cstring> |
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#include<string> |
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#include<sstream> |
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#include<cmath> |
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#include<vector> |
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#include<queue> |
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#include<cstdlib> |
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#include<deque> |
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#include<stack> |
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#include<map> |
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#include<set> |
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#define __FastIO ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0) |
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#define __FileRead freopen ("input.txt", "r", stdin); |
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#define __FileWrite freopen ("output.txt", "w", stdout); |
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#define SET(a,v) memset(a,v,sizeof(a)) |
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#define pii pair<int,int> |
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#define pll pair <ll, ll> |
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#define debug cout <<"#########\n"; |
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#define nl cout << "\n"; |
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#define sp cout << " "; |
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#define sl(n) scanf("%lld", &n) |
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#define sf(n) scanf("%lf", &n) |
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#define si(n) scanf("%d", &n) |
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#define ss(n) scanf("%s", n) |
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#define pf(n) scanf("%d", n) |
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#define pfl(n) scanf("%lld", n) |
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#define all(v) v.begin(), v.end() |
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#define Pow2(x) ((x)*(x)) |
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#define Mod(x, m) ((((x) % (m)) + (m)) % (m)) |
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#define Max3(a, b, c) max(a, max(b, c)) |
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#define Min3(a, b, c) min(a, min(b, c)) |
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#define pb push_back |
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#define mk make_pair |
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#define MAX 105 |
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#define INF 1000000000 |
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#define MOD 1000000007 |
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using namespace std; |
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typedef long long ll; |
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typedef unsigned long long ull; |
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template <typename T> |
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std::string NumberToString ( T Number ) { |
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std::ostringstream ss; |
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ss << Number; |
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return ss.str(); |
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} |
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ll lcm (ll a, ll b) { |
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return a * b / __gcd (a, b); |
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} |
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int tree[MAX * 4][MAX * 4]; |
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int vec[MAX][MAX]; |
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int n, m, mx; |
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void build (int indx, int nod, int low, int high) { |
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if (low == high) { |
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tree[indx][nod] = low; |
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return ; |
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} |
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int mid = (high + low) / 2; |
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int left = nod * 2; |
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int right = nod * 2 + 1; |
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build (indx, left, low, mid); |
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build (indx, right, mid + 1, high); |
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if (vec[indx][tree[indx][left]] <= vec[indx][tree[indx][right]]) { |
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tree[indx][nod] = tree[indx][left]; |
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} else { |
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tree[indx][nod] = tree[indx][right]; |
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} |
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} |
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int query (int indx, int nod, int low, int high, int qlow, int qhigh) { |
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if (qlow > high || qhigh < low) { |
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return 0; |
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} |
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if (qlow <= low && qhigh >= high) { |
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return tree[indx][nod]; |
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} |
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int mid = (high + low) / 2; |
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int left = nod * 2; |
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int right = nod * 2 + 1; |
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int a = query (indx, left, low, mid, qlow, qhigh); |
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int b = query (indx, right, mid + 1, high, qlow, qhigh); |
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if (vec[indx][a] <= vec[indx][b]) { |
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return a; |
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} else { |
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return b; |
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} |
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} |
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void solve (int indx, int l, int r) { |
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if (l > r) return ; |
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int idx = query (indx, 1, 1, m, l, r); |
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int xx = vec[indx][idx] * (r - l + 1); |
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mx = max (mx, xx); |
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solve (indx, l, idx - 1); |
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solve (indx, idx + 1, r); |
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} |
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int main () { |
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__FastIO; |
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while (cin >> n >> m) { |
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if (n == 0 && m == 0) break; |
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SET (tree, 0); |
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SET (vec, 0); |
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int ar[MAX][MAX]; |
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for (int i = 1; i <= n; i++) { |
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for (int j = 1; j <= m; j++) { |
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cin >> ar[i][j]; |
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} |
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} |
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for (int i = 1; i <= n; i++) { |
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for (int j = 1; j <= m; j++) { |
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if (i == 1) { |
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if (ar[i][j] == 0) { |
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vec[i][j] = 1; |
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} else { |
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vec[i][j] = 0; |
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} |
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} else { |
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if (ar[i][j] == 0) { |
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vec[i][j] = vec[i - 1][j] + 1; |
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} else { |
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vec[i][j] = 0; |
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} |
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} |
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} |
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} |
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for (int i = 0; i < MAX; i++) { |
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vec[i][0] = 1000000; |
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} |
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int ans = 0; |
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for (int i = 1; i <= n; i++) { |
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build (i, 1, 1, m); |
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} |
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for (int i = 1; i <= n; i++) { |
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mx = 0; |
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solve (i, 1, m); |
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ans = max (ans, mx); |
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} |
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cout << ans << "\n"; |
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} |
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return 0; |
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} |
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