#include<bits/stdc++.h>
using namespace std;
int main(){
    int a;
    const double b=0.4463,c=0.4663,d=05663;
    double e=0;
    cin>>a;
    if(a<=150){
        e=a*b;
    }
    else if(a>=151&&a<=400){
        e+=150*b;
        e+=(a-150)*c;
    }
    else{
        e+=150*b;
        e+=250*c;
        e+=(a-400)*d;
    }
    printf("%.1lf",e);
    return 0;
}