#遍历的时候可以直接从最长的开始排除,比较快 s1 = input() s2 = input() if len(s1)>len(s2): s1,s2 = s2,s1 isprint = 0 #已保证s1<s2 for ll in range(len(s1),0,-1): for i in range(0,len(s1)-ll+1): ss = s1[i:i+ll] if s2.count(ss) != 0: print(ss) isprint = 1 break if isprint == 1: break