#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	double s;
    cin >> n;
    if(n <= 150) 
	{
		s = 0.4463 * n;
	}
    if(n >= 151 && n <= 400) 
	{
		s = 0.4463 * 150 + 
		(n - 150) * 0.4663;
	}
    else 
	{
		s = 0.4463 * 150 + (400 - 150) * 0.4663 
		+(n - 400) * 0.5663;
	}
    printf("%.1f",s);
    return 0;
}