最后一题 import sys def getRelationExtend(p,r,relations):     list1=relations[p]     listLen=len(list1)     for p2 in r:         list2=relations[p2]         for l in list2:             if l not in list1 and l != p:                 list1.append(l)     if len(list1)==listLen:         return relations[p]     else:         newAdd=list1[listLen:]         relations[p]=list1         return getRelationExtend(p,newAdd,relations)               s=sys.stdin.readline().strip() data=[] while s != '':     s=list(map(int,s.split()))     data.append(s)     s=sys.stdin.readline().strip() n=data[0][0] m=data[1][0] myrelations={} relations=data[2] for i in range(m):     if relations[2*i-1] not in myrelations:         myrelations[relations[2*i-1]]=[relations[2*i-2]]     else:         if relations[2*i-2] not in myrelations[relations[2*i-1]]:             myrelations[relations[2*i-1]].append(relations[2*i-2])         else:             pass for i in range(n):     if i+1 not in myrelations:         myrelations[i+1]=[] count=0 for p in myrelations:     pRelations=myrelations[p]     r=getRelationExtend(p,pRelations,myrelations)     myrelations[p]=r     if len(r) == n-1:         count+=1      print(count)