#include<bits/stdc++.h>
using namespace std;

int main()
    {
    long long a;
    double b;
    a=0;
    b=0;
    cin>>a;
        if(a<=150)
    {
        b = a*0.4463;
    }
    else if(a>=151&&a<=400)
    {
        b += 150*0.4463;
        b += (a-150)*0.4663;
    }
    else
    {
        b += 150*0.4463;
        b += (400-150)*0.4663;
        b += (a-400)*0.5663;
    printf("%.1lf",b);
    return 0;
    }