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

else
   a=n*2.0;
printf("%.1f",a);
return 0;
}

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