def get_new_position(old_position, move):
    """
    get new position based of current position of the man and move direction
    """
    if move == 'l':
        new_position = [old_position[0] - 1, old_position[1]]
    elif move == 'r':
        new_position = [old_position[0] + 1, old_position[1]]
    elif move == 'u':
        new_position = [old_position[0], old_position[1] - 1]
    elif move == 'd':
        new_position = [old_position[0], old_position[1] + 1]
    else:
        print('invalid move')
        new_position = old_position
    return new_position