"""
출처:프로그래머스,
https://school.programmers.co.kr/learn/courses/30/lessons/42577
"""
# 풀이과정
def solution(phone_book):
    p = phone_book

    p.sort()

    for a in range(len(p) - 1):
        if p[a] in p[a + 1][0:len(p[a])]:
            return False

        else:
            continue

    return True