#include<bits/stdc++.h>
using namespace std;
int main() {
    int n;
    cin>>n;
    if(n>=90){
        cout<<n*3;
    }else if(n>=80){
        cout<<n*2;
    }else if(n>=70){
        cout<<n;
    }else{
        cout<<50;
    }
    return 0;
}
/**************************************************************
	Problem: 1300
	User: panjinyan
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/