求解

#include<bits/stdc++.h>
using namespace std;
int n,m,x,y;
double s,s1; 
int main(){   
    cin>>x>>y>>m>>n;
    s=n-y;
  	s1=n*m*1.00/10;
    if(s<s1){
    	printf("%.2lf\n",s);
    }else{
    	printf("%.2lf\n",s1);
    }
    return 0;
}