#include<bits/stdc++.h>
using namespace std;
int main()
{
	float a,money=0;
	cin>>a;
	if(a>=150)
	{
		money=a*0.4463;
		cout<<std::fixed<<setprecision(1)<<money;
		return 0;
	}
	if(a>=400)
	{
		money=150*0.4463+(a-150)*0.4663;
		cout<<std::fixed<<setprecision(1)<<money;
		return 0;
	}
	money=150*0.4463+250*0.4663+(a-400)*0.5663;
	cout<<std::fixed<<setprecision(1)<<money; 
	return 0;
}