#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    float h;
    cin>>n;
    if(n<=150){
    	h=n*0.4463;
    	printf("%.1f",h);
    }else if(n>=151&&n<=400){
    	h=n*0.4663;
    	printf("%.1f",h);
    }else if(n>=401){
    	h=n*0.5663;
    	printf("%.1f",h);
    }
	
}

/**************************************************************
	Problem: 1463
	User: yangjunwen
	Language: C++
	Result: Wrong Answer
****************************************************************/