#include <bits/stdc++.h>

using namespace std;

int main() {
    int old;
    cin >> old;
    if (old <= 50) cout << old << endl;
    if (old > 50 && old <= 150) cout << 50 + (old - 50) * 0.9 << endl;
    if (old > 150) cout << 50 + (150 - 50) * 0.9 + (old - 150) * 0.8 << endl;
    return 0;
}