n = input().strip() 哎,笨脑子还是觉得取余最好用,内置函数脑子转不过来的说 ni = n[::-1] fen = [] for i in range(0,len(ni),3): fen.append(ni[i:i+3]) resni =','.join(fen) res = resni[::-1] print(res) # n = int(input()) # res = [] # while n>0: # a = n%1000 # n = n//1000 # res.append(str(a)) # ans = ','.join(reversed(res)) # p...