#include<bits/stdc++.h>
using namespace std;
int main(){
	int a,s1,s2=0;
	double sum;
	cin>>a;
	if(a<=150){
		sum=a*0.4463;
	}else{
		s1=a-150;
		if(s1>400-151){
			s1=400-151;
			s2=a-s1;
		}
		sum=150*0.4463+s1*0.4663+s2*0.5663;
	}
	printf("%.1lf",sum);
	return 0;
}