#include<bits/stdc++.h>
using namespace std;
int n;
double s;
int main()
{
	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);
}