#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
	cin>>n;
	float b;
	if(n<10){
		b=n*2.2;
	}
	else{
		b=n*2;
	}
	printf("%.1f",b); 
return 0;
}

/**************************************************************
	Problem: 1303
	User: chenzelin
	Language: C
	Result: Compile Error
****************************************************************/