kotori和bangdream

 

#include<cstdio>
#include<iostream>
using namespace std;
int n,x,a,b;
int main() {
    cin>>n>>x>>a>>b;
    double ans=n*(a*x*1.0/100+b*(100-x)*1.0/100);
    printf("%.2lf",ans);
    return 0;
}