private static void Main(string[] args)
{
int n = int.Parse(Console.ReadLine());
while (n != 0)
{
counter = 0;
N = n;
A = new int[N];
//initialize each to i
for (int i = 0; i < N; i++)
A[i] = i;
//enumerate starting from 0
enumerate(0);
Console.WriteLine("N={0}: {1} permutations", n, counter);
n = int.Parse(Console.ReadLine());
}
}