#include <bits/stdc++.h>
using namespace std;
int main(){
   int a;
   double b;
   cin>>a;
   if(a >= 10){
   	  b = a * 2;
   }else{
   	  b = a * 2.2;
   }
   cout<<fixed<<setprecision(1)<<b<<endl;
   return 0;
}

/**************************************************************
	Problem: 1303
	User: admin
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/