#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	if(n>=10)
	{
		printf("%.1f",n*1.0*2);
	}
	else printf("%.1f",n*2.2);



	return 0;
}

/**************************************************************
	Problem: 1303
	User: 21A
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/