# 20240920
a = input()
b = input()
if len(a) > len(b):
    a,b = b,a
s = ''
for i in range(0,len(a)):
    for j in range(i+1,len(a)+1):
        if a[i:j] in b and j-i > len(s):
            s = a[i:j]
print(s)