题解 | #查找两个字符串a,b中的最长公共子串#

s1 = input().lower()
s2 = input().lower()

p = 0
if len(s1) > len(s2):
    s1, s2 = s2, s1

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