import sys, math num = int(sys.stdin.readline().strip()) ret = '' # 判断质数 def iz(k): if k == 1: return 0 if k in (2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37): return 1 for i in (2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37): if k % i == 0: return 0 ...