text: /*
  *Author: Fabian Calsina
  *Date: -
  */
  #include <bits/stdc++.h>
  
  using namespace std;
  
  int main()
  {
      int a,b;
  
      while(scanf("%d %d", &a, &b) != EOF)
      {
          printf("%d\n", a * b * 2);
      }
  return 0;
  }
  