#include<iostream>
using namespace std;
int main() {
    int n, a;
    cin >> n;
    if (n >= 90) {
        a = n * 3;
    } else if (n >= 80) {
        a = n * 2;
    } else if (n >= 70) {
        a = n;
    } else {
        a = 50;
    }
    cout << a;
    return 0;
}
/**************************************************************
	Problem: 1300
	User: panyuchen
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/