#include<bits/stdc++.h>
using namespace std;
int main(){
	int c,q;
	cin>>c;
	if(c>=90){
		q=c*3;
		cout<<q;
	}
	if(c>=80 && c<90){
		q=c*2;
		cout<<q;
	}
	if(c>=70 && c<80){
		cout<<c;
	}
	if(c<70){
		cout<<50;
	} 
	
} 

/**************************************************************
	Problem: 1300
	User: zhengzihao3
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/