#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<80&&n>=70){
    	cout<<n;
    }else if(n<70){
    	cout<<50;
    }
} 
/**************************************************************
	Problem: 1300
	User: yangjunwen
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/