题解 | #查找两个字符串a,b中的最长公共子串#

s1 = input().strip()


s2 = input().strip()
if len(s1) > len(s2):
    s1, s2 = s2, s1
n = len(s1)
m = len(s2)

res = ''
for i in range(n):
    for j in range(i+1,n):
        if s1[i:j+1] in s2 and j+1-i > len(res):
            res = s1[i:j+1]

print(res)