#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	long double sum;
	if(n<=150)
	{
		sum=n;
		sum*=0.4463;
	}
	else if(151<=n && n<=400)
	{
		sum=150*0.4463;
		n*=0.4663;
		sum+=n;
	}
	else if(401<=n)
	{
		sum=150*0.4463+249*0.4663;
		n*=0.5663;
		sum+=n;
	}
	cout<<fixed<<setprecision(1)<<sum;
	return 0;
}