题解 | #查找两个字符串a,b中的最长公共子串#

# 20240920
a = input()
b = input()
if len(a) > len(b):
    a,b = b,a
ls = []
for i in range(0,len(a)):
    for j in range(i+1,len(a)+1):
        if a[i:j] in b:
            ls.append(a[i:j])
ls.sort(key=lambda x:len(x),reverse=True)
print(ls[0])