#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
	int n; double m;
	cin >> n;
	if (n <= 150) m = n * 0.4463;
	else 
	{
		if (n <= 400) m = (n-150) * 0.4663+150*0.4463;
		else m = (n-400) * 0.5663+250*0.4663+150*0.4463;
	}
	cout <<setiosflags(ios::fixed)<<setprecision(1)<< m; 
	return 0;
}