bool IsValidWalk(string[] walk)
{
    if (walk.Length != 10)
    {
        return false;
    }
    var Map = new List<int> { 0, 0 };
    foreach (string Direction in walk)
    {
        switch (Direction)
        {
            case "n": Map[0] += 1; break;
            case "s": Map[0] -= 1; break;
            case "w": Map[1] += 1; break;
            case "e": Map[1] -= 1; break;
        }
    }
    if ((Map[0] == 0) && (Map[1] == 0))
        return true;
    else return false;
}