t = input()
for i in t:
    if (ord(‘a‘) <= ord(i) <= ord(‘z‘)):
        t = chr(ord(‘a‘)+(ord(i)-ord(‘a‘)+3)%26)
        print(t,end=‘‘)
    elif  (ord(‘A‘) <= ord(i) <= ord(‘Z‘)):
        t = chr(ord(‘A‘)+(ord(i)-ord(‘A‘)+3)%26)
        print(t,end=‘‘)
    else:
        t = i
        print(t,end=‘‘)
原文:https://www.cnblogs.com/kwjl/p/12555115.html