def find_neighbors(start_coordinate, matrix):
    """
    The function finds all neighbors of start_coordinate,but not includes itself.
    :param start_coordinate: [y,x]
    :param matrix: 4x4 alphabet
    :return: neighbor_position_lst: a list of letters and coordinates of neighbors [[letter1,[y1,x1]],[letter2,[y2,x2]],....]
    """
    neighbor_position_lst = []
    x = start_coordinate[1]
    y = start_coordinate[0]
    for i in range(-1, 2):  # getting neighbors' coordinates by using -1,0,1 to permute
        for j in range(-1, 2):
            letter_x = x + i
            letter_y = y + j
            if 0 <= letter_x <= len(matrix[y]) - 1:
                if 0 <= letter_y <= len(matrix) - 1:
                    if letter_x != x or letter_y != y:
                        letter_and_absolute_position_index = [matrix[letter_y][letter_x], [y + j, x + i]]
                        neighbor_position_lst.append(letter_and_absolute_position_index)
    return neighbor_position_lst