#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: houlingqi2
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/