#include <iostream>
#include <iomanip>
using namespace std;
int main ()
{
int n;
cin>>n;
float count=0;
if(n<=150)
count=0.4463*n;
else if(n>=151 && n<=400)
count=0.4663*(n-150)+150*0.4463;
else
count=0.5663*(n-400)+150*0.4463+(400-150)*0.4663;
cout<<setiosflags(ios::fixed)<<setprecision(1)<<count;
return 0;
}