#include <bits/stdc++.h>
using namespace std;
int main()
{
int n;
cin>>n;
if(n>=10)
cout<<n*2;
else
cout<<n*2.2;
	return 0;
}

/**************************************************************
	Problem: 1303
	User: wqc123
	Language: C++
	Result: Wrong Answer
****************************************************************/