#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	double a,t; 
	cin>>n;
	if(n>=10){
		a=n*2.0;
		cout<<a;	
	}	
	else {
		t=n*2.2;	 
		printf("%.1f",t);
	}		
	return 0;
}

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