import sys s1 = input() s2 = input() if len(s1) > len(s2): s1,s2 = s2,s1 window = '' max_len = 0 l = 0 r = 1 while r < len(s1): if s1[l:r] in s2: if r-l > max_len: max_len = r-l window = s1[l:r] r += 1 else: l = max(l + 1,r - 2) # r = r + 1 print(window)