#include <bits/stdc++.h>
using namespace std;
int a;
int b;
int main() {
    cin>>b;
    if (b>400) a=150*0.4463+250*0.4663+(b-400)*0.5663;
    if (b>150) a=150*0.4463+(b-150)*0.4663;
    if (b<=150) a=b*0.4463;
    cout<<floor(a*10+0.5)/10.0<<endl;
    return 0;
}