#include <bits/stdc++.h>
#define INF INT_MAX
#define miniF INT_mini
#define ll long long
#define ull unsigned long long
#define ld long double
#define PB push_back 
#define PF push_front
#define P_F pop_front
#define P_B pop_back
#define F front
#define B back
#define f first
#define s second
#define MP make_pair
#define FOR(i, a, b) for(ll i = a; i < b; i++)
#define FORI(i, a, b) for(ll i = a; i >= b; i--)
#define PI 3.14159265358979323846
 
using namespace std;
 
const ld EPSILON = 0.0000001;
 
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
 
  int v, t;
 
  while(cin >> v >> t) {
    cout << v*t*2 << '\n';
  }
 
  return 0;
}

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