#include<bits/stdc++.h> 
using namespace std;
int main()
{
	int n;
	cin>>n;
	float s;
	if(n>10){
		s=2.0*n;
	}
	else{
		s=2.2*n;
	}
	printf("%.1f",s);
	return 0; 
}
/**************************************************************
	Problem: 1303
	User: dengyuanyan
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/