#include <bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    double sum;
    cin >> n;
    if (n <= 150)
    {
        sum = n * 0.4463;
    }

    if (n >= 151 && n <= 400)
    {
        sum = (n - 150) * 0.4663 + 150 * 0.4463;
    }
    else
    {
        sum = (n - 400) * 0.5663 + 150 * 0.4463 + (400 - 151 + 1) * 0.4663;
    }
    cout << fixed << setprecision(1) << sum;

    return 0;
}