#include <cstdio>
int main(){
int v = 0, t = 0;
while (scanf("%d%d", &v, &t) != EOF){
printf("%d\n", 2 * v * t);
}
return 0;
}
#include <cstdio>
int main(){
int v = 0, t = 0;
while (scanf("%d%d", &v, &t) != EOF){
printf("%d\n", 2 * v * t);
}
return 0;
}