void visit(int *Value, int N, int k)
{
    int i;
  static level = -1;
  level = level+1; Value[k] = level;

  if (level == N)
    print(Value, N);
  else
    for (i = 0; i < N; i++)
      if (Value[i] == 0)
        visit(Value, N, i);

  level = level-1; Value[k] = 0;
}