#include<bits/stdc++.h>
using namespace std;
int main(){
   int n;
   int a=150*0.4463,b=250*0.4663;
   cin>>n;
   if(n<=150)
   	printf("%.1lf",n*0.4463);
   else if(n>150&&n<=400) 
   	printf("%.1lf",a+(n-150)*0.4663);
   else 
   	printf("%.1lf",a+b+(n-400)*0.5663);
   return 0;
}