#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	if(n<=150){
		cout<<fixed<<setprecision(1)<<n*0.4463;
	}
	if(n>150&&n<=400){
		cout<<fixed<<setprecision(1)<<150*0.4463+(n-150)*0.4663;
	}
	if(n>=401){
		cout<<fixed<<setprecision(1)<<150*0.4463+250*0.4463+(n-400)*0.5663;
	}
}