#include <bits/stdc++.h>
using namespace std;
int n;
double ans;
int main()
{
	cin >> n;
	if(n <= 150) ans = n * 0.4463;
	else if(n <= 400) ans = 150 * 0.4463 + (n - 150) * 0.4663;
	else ans = 150 * 0.4463 + (400 - 150) * 0.4663 + (n - 400) * 0.5663;
	ans = int((ans * 10) + 0.5) / 10.0;
	printf("%.1llf", ans);
	return 0;
}