#include<bits/stdc++.h>
using namespace std;
int main(){
    double a;
    cin>>a;
    if(a<=150)printf("%.1lf",0.4463*a);
    if(a<=400 and a>150)printf("%.1lf",0.4663*(a-150)+0.4463*150);
    if(a>400)printf("%.1lf",0.5663*(a-400)+0.4463*150+0.4663*250);
    return 0;
}