#include<bits/stdc++.h>
using namespace std;
int main(){
	float n;
	cin>>n;
	if(n>10){
		cout<<n*2;
	}else{
		cout<<n*2.2;
	}
	return 0;
}
/**************************************************************
	Problem: 1303
	User: chenyaohuo
	Language: C++
	Result: Wrong Answer
****************************************************************/