请进行测试用例设计:一串数字,闰年的判别
#!/usr/bin/python
# -*- coding: utf-8 -*-
year = int(input())
if year <= 0 and year > 9999:
print("Please enter a proper year.")
if year%4 == 0 and year%100 != 0 or year%400 == 0:
print("Yes.")
else:
print("No.")