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