2013秋13级预备队集训练习1 B - Back to High School Physics

 

#include<stdio.h>
int main()
{
 int a , b , c ;
 while(scanf("%d %d", &a, &b)!=EOF)
 {
  c = 2*a*b;
  printf("%d\n", c);
 }
 return 0;
}