10071 - Back to High School Physics

#include <stdio.h>

int main(){

    int  s, a, b;

    while(scanf("%d %d", &a, &b) != EOF){  // for End of File Input
        s = 2 * a * b;
        printf("%d\n", s);
    }

    return 0;
}



   // while(scanf("%d %d", &a, &b) != EOF){  //way --1. for end of file
   // while(scanf("%d %d", &a, &b) == 2){   // way --2. for end of file

   //while(scanf("%d %d", &a, &b)){          //way --3. for end of file