a=input()
b=10
while b>0:
if a.isdigit() and int(a)<=1000:
a=int(a)
break
elif a.isdigit():
a=input("數字大於1000請重新輸入")
else :
a=input("這不是數字請從新輸入")

if a%7==0:
print(a,"是七的倍數")
else :
print(a,"不是七的倍數")