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#include <iostream> |
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#include <vector> |
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#include <utility> |
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#include <algorithm> |
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using namespace std; |
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typedef pair<int, int> ii; |
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int main() { |
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int N; |
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cin >> N; |
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while (N--) { |
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int M; |
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cin >> M; |
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int L, R; |
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vector<ii> v; |
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while (cin >> L >> R && !(L == 0 && R == 0)) v.push_back(make_pair(L, R)); |
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sort(v.begin(), v.end()); |
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vector<ii> sol; |
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int last = 0; |
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bool covered = false; |
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for (int i = 0; i < v.size() && !covered; i++) { |
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if (v[i].first > last) break; |
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ii maxi = v[i]; |
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while (i < v.size() && v[i].first <= last) { |
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if (v[i].second > maxi.second) maxi = v[i]; |
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i++; |
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} |
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if (i < v.size()) i--; |
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if (maxi.second > last) { |
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last = maxi.second; |
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sol.push_back(maxi); |
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} |
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if (last >= M) covered = true; |
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} |
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if (covered) { |
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printf("%d\n", sol.size()); |
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for (int i = 0; i < sol.size(); i++) printf("%d %d\n", sol[i].first, sol[i].second); |
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} else printf("0\n"); |
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if (N != 0) printf("\n"); |
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} |
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return 0; |
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} |
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