#include<cstdio>
#include<iostream>
#include<cmath>
using namespace std;
int main(){
	int a=0;
	double n=0.0;
	scanf("%d",&a);
	if(a<=150){
		n=0.4463*a*1.0;
//		cout<<n;
		printf("%.1lf",n);
	}else if(a<=400||a>150){
		n+=0.4463*150;
		n+=0.4663*(a-150);
//		cout<<n;
		printf("%.1lf",n);
	}else{
		n+=0.4463*150;
		n+=0.4663*(a-150);
		n+=0.5663*(a-400);
//		cout<<n;
		printf("%.1lf",n);
	}	
//    cout<<floor(n*10+0.5)/10.0;
}