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