def leapYear(n):
return n%4==0 and n%100!=0 or n%400==0
while True:
n=input('请输入年份:')
if n=='stop':
print('Bye!')
break
if not n.isdigit() or int(n)<0:
print('错误,请重新输入!')
continue
n=int(n)
if leapYear(n):
print('Yes')
else:
print('No')