很简单直接运算即可，由于数据很小开int即可AC

include <bits/stdc++.h>

using namespace std;
int x,y,z,t;
double ans;
int main()
{
scanf("%d%d%d%d",&t,&x,&y,&z);
ans=xy/(double)8z*t;
ans=ans/(double)1024/(double)1024;
printf("%0.4lf",ans);
}