#include<bits/stdc++.h>
using namespace std;
long long n,x,y,z;
long double m;
int main(){
    cin>>n;
    if(n>150){
        m = 150*0.4463*0.0001;
        if(n>400){
            m = 250*0.4663*0.0001+m;
            cout<<fixed<<setprecision(1)<<m+(n-400)*0.4663;
        }else{
            cout<<fixed<<setprecision(1)<<m+(n-150)*0.5663;
        }
    }else{
        cout<<fixed<<setprecision(1)<<n*0.4463;
    }
	return 0;
}