/*
  >>~~ UVa Online Judge ACM Problem Solution ~~<<

  ID: 10071
  Name: Back to High School Physics
  Problem: https://onlinejudge.org/external/100/10071.pdf
  Language: C++

  Author: Arash Shakery
  Email: arash.shakery@gmail.com
*/

#include <stdio.h>
#include <iostream>
using namespace std;

int main(){
    int v, t;
    while(cin>>v>>t)
        cout<<2*v*t<<endl;
}