#include<bits/stdc++.h>
using namespace std;
int main(){ 
	float j; 
	int n;
	cin>>n;
	if(n<=150){
		j=n*0.4463;
		printf("%.1f",j);
	}else if(n>500&&n<=400){
		j=150*0.4463+(n-150)*0.4663;
		printf("%.1f",j);
	}else if(n>400){
		j=150*0.4463+250*0.4663+(n-400)*0.5663;
		printf("%.1f",j);
	}
}
/**************************************************************
	Problem: 1463
	User: wangyiyang
	Language: C
	Result: Compile Error
****************************************************************/