a = str(input())
b = str(input())

#让a的长度小于或者等于b
if len(a) > len(b):
    a, b = b, a

n = 0
res = ""
for i in range(len(a)):
    for j in range(1, len(a)+1):
        if a[i:j] in b: #如果a的子串在b之内
            if len(a[i:j]) > n:
                n = len(a[i:j])
                res = a[i:j]
print(res)