#include <bits/stdc++.h>
using namespace std;
int main(){
	int a,t;
	cin>>a;
	if(a>=90)t=a*3;
	else if(a>=80)t=a*2;
		else if(a>=70)t=a;
			else cout<<"50";
	cout<<t;
	return 0;
	}

/**************************************************************
	Problem: 1300
	User: ljl2
	Language: C++
	Result: Wrong Answer
****************************************************************/