#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
	cin>>n;
	float s;
	if(n<10){
		s=n*2.2;
	}
	else{
		s=n*2;
	}
	printf("%.1f",s); 
return 0;
}

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