#!/usr/bin/env python
#coding:utf-8
import time
while True:
start_time = raw_input("输入开始日期：")
if not start_time.isdigit():
print "输入有误！日期格式为年-月-日"
break
else:
end_time = raw_input("输入结束日期：")
# break
if not end_time.isdigit():
print "输入有误！日期格式为年-月-日"
break
else:
print "============================"
time.sleep(2)
if start_time >= end_time:
print "开始日期必须小于结束日期"
break
else:
print "开始查询"
break