List<int> TakeWhile(List<int> data, Func<int, int, bool> f)
{
    List<int> result = new List<int>();
    int index = 0;
    bool isTake = false;
    foreach (int i in data)
    {
        if (!isTake && f(i, index)) isTake = true;
        if (isTake) result.Add(i);
    }
    return result;
}