#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	double x;
	cin>>n;
	if(n<=150){
		x=n*0.4463;
	}else{
		x=0.4463*150;
		if(n<=400){
			x+=(n-150)*0.4663;
		}else{
			x+=(400-150)*0.4663;
			x+=(n-400)*0.5663;
		}
	}
	printf("%.1f",x);
	return 0;
}

/**************************************************************
	Problem: 1463
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/