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

    
  
/**************************************************************
	Problem: 1300
	User: fandaohan
	Language: C++
	Result: Accepted
	Time:27 ms
	Memory:2072 kb
****************************************************************/