#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float q;
	cin>>n;
	if (n<=150){
		q=n*0.4463;
	}
	else if (151<=n && n<=400){
		q=150*0.4463+(n-150)*0.4663;
	}
	else {
		q=150*0.4463+(400-150)*0.4663+(n-400)*0.5663;
	}
	printf("%.1f",q);
	return 0;
}
/**************************************************************
	Problem: 1463
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:23 ms
	Memory:2072 kb
****************************************************************/