#include<bits/stdc++.h>
using namespace std;
int main() {
	int n;
	cin>>n;
	if(n>=90) cout<<n*3;
	else if(n>=80&&n<90) cout<<n*2;
	else if(n>=70&&n<80) cout<<n;
	else cout<<50;
	
}
/**************************************************************
	Problem: 1300
	User: linzihang
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/