#include<bits/stdc++.h>
using namespace std;
int n;
double ans;
int main(){
	cin>>n;
	if(n<=150) ans=n*0.4463;
	else if(n>150&&n<=400) ans=150*0.4463+(n-150)*0.4663;
	else ans=150*0.4463+350*0.4663+(n-400)*0.5663;
	printf("%.1lf",ans);
	return 0;
}