b=""

c=input("请输入明文：")

for i in range(len(c)):

if 'a'<=c[i]<='w' or 'A'<=c[i]<='W':

b+=chr(ord(c[i])+3)

elif 'x'<=c[i]<='z' or 'X'<=c[i]<='Z':

b+=chr(ord(c[i])-23)

else:

b+=c[i]

print("加密后的密文是：",b,sep='')