# -*- coding: utf-8 -*-
"""
Created on Mon May 29 14:20:44 2017

@author: Administrator
"""

plaincode = input("请输入明文：")
for p in plaincode:
    if ord("a") <= ord(p) <= ord("z"):
        print(chr(ord("a") + (ord(p) - ord("a") + 3) % 26),end ='')
    else:
        print(p, end = '')
1ce4464f5586d745bf06411a1d8e9cfbb18a3153
<mask token>

<mask token>
for p in plaincode:
    if ord('a') <= ord(p) <= ord('z'):
        print(chr(ord('a') + (ord(p) - ord('a') + 3) % 26), end='')
    else:
        print(p, end='')

<mask token>
plaincode = input('请输入明文：')
for p in plaincode:
    if ord('a') <= ord(p) <= ord('z'):
        print(chr(ord('a') + (ord(p) - ord('a') + 3) % 26), end='')
    else:
        print(p, end='')

# -*- coding: utf-8 -*-
"""
Created on Mon May 29 14:20:44 2017

@author: Administrator
"""

plaincode = input("请输入明文：")
for p in plaincode:
    if ord("a") <= ord(p) <= ord("z"):
        print(chr(ord("a") + (ord(p) - ord("a") + 3) % 26),end ='')
    else:
        print(p, end = '')