题解 | #查找两个字符串a,b中的最长公共子串#

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