num = input('請輸入數字0~1000')
while num.isdigit() == False or int(num) not in range (0, 1001):
    print('輸入不為0~1000的數字，請重新輸入')
    num = input('請重新輸入0~1000的數字')
if int(num) % 7 == 0 : print(num,'是7的倍數')
else : print (num,'不是7的倍數')