def common(a,b): l=[] for i in range(len(a)): j=1 while b.find(a[i:][:j])!=-1 and j<=len(a):j+=1 if j>1:l+=[a[i:][:j-1]] return sorted(l,cmp,len,1)[0] a=raw_input() while 1: print a b=raw_input() c=common(a,b) i=a.find(c) j=b.find(c) b=" "*(i-j)+b a=b
Note that non-ascii characters in the above source code will be escaped (such as \x9f).