#include <iostream>
using namespace std;
int main()
{
	int a;
	cin >> a;
	if (a>=90)
	{
		cout << 3*a;	
	}
	else if (80<=a<90)
	{
		cout << 2*a;
	}
	else if (70<=a<80)
	{
		cout << a;
	}
	else
	{
		cout << 50;
	}
}
/**************************************************************
	Problem: 1300
	User: xiaomingze
	Language: C++
	Result: Wrong Answer
****************************************************************/