#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	double sum=0;
	cin>>n;
	if(n<=150) sum+=n*0.4463;
	else if(n<=400) sum+=150*0.4463+(n-150)*0.4663;
	else sum+=150*0.4463+400*4663+(n-400)*0.5663;
	cout<<fixed<<setprecision(1)<<sum<<endl;
	return 0;
}