[ZJd226][UVA10071] Back to High School Physics

題目：
http://zerojudge.tw/ShowProblem?problemid=d226
================================================================
#include<cstdio>
int main(void)
{
int v, t;
while(scanf("%d%d",&v,&t)!=EOF)
{
printf("%d\n",v*t*2);
}
return 0;
}