#include<bits/stdc++.h>
using namespace std;
int main()
{
float y;
int n;
cin>>n;
if(n<10)
	y=n*2.2;
else
	y=n*2.0;

printf("%.1f",y);
return 0;
}





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