#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float i=0;
	cin>>n;
	if(n<10){
	 i=n*2.2;	
	}else{
		i=n*2;
	}
	printf("%.1f",i);
}
/**************************************************************
	Problem: 1303
	User: huxuanchen
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/