#include<bits/stdc++.h>
using namespace std;
int main()
{
    long long n;
    cin>>n;
    if(n>=90) n=n*3;
    else if(n>=80) n=n*2;
         else if(n>=70) n=n;
              else if(n<70) n=50;
    cout<<n;
    return 0;
}
/**************************************************************
	Problem: 1301
	User: lijinkai
	Language: C++
	Result: Wrong Answer
****************************************************************/