题解 | #查找两个字符串a,b中的最长公共子串#

while True:
    try:
        s1 = input().strip()
        s2 = input().strip()
    except EOFError:
        break
    if len(s1) > len(s2):
        s1, s2 = s2, s1
    ret = ''
    for start in range(len(s1)):
        for end in range(start+1, len(s1)+1):
            sub = s1[start:end]
            if len(sub) > len(ret) and sub in s2:
                ret = sub
    print(ret)