#include<bits/stdc++.h>
using namespace std;
int a;
int main(){
	cin>>a;
	if(a<10) printf("%.1lf",a*2.2);
	else printf("%.1lf",a*2.0);
	return 0;
}
/**************************************************************
	Problem: 1303
	User: zhangziang
	Language: C++
	Result: Accepted
	Time:16 ms
	Memory:2072 kb
****************************************************************/