#include<bits/stdc++.h>
using namespace std;
int n;
double ans;
int main()
{
	cin>>n;
	if(n<=150){
		ans=n*0.4463;
		cout<<ans;
	}
	else if(n<=400){
		ans=150*0.4463;
		n-=150;
		ans+=n* 0.4663;
		cout<<ans;
	}
	else{
		cout<<150*0.4463+249*0.4663+(n-400)*0.5663;
	}
	return 0;
}