#include<bits/stdc++.h>
using namespace std;
int n;
double ans;
int main(){
   cin>>n;
   if(n>0&&n<=150)
   {
		ans=n*0.4463;
   }
   else if(n>150&&n<=401)
   {
		ans=150*0.4463;
		n-=150;
		ans+=n*0.4663;
   }
   else
   {
		ans=150*0.4463;
		ans+=251*0.4663;
		n-=401;
		ans+=n*0.5663;
   }
   cout<<fixed<<setprecision(1)<<ans;
   return 0;
}