#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	if(n>=90) cout<<n*3;
	if(n>=80&&n<90) cout<<n*2;
	if(n>=70&&n<80) cout<<n;
	if(n<70) cout<<50;
}
/**************************************************************
	Problem: 1300
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:26 ms
	Memory:2072 kb
****************************************************************/