https://programmers.co.kr/learn/courses/30/lessons/12926
def solution(s, n):
answer = ''
for i in s:
if i.isupper():
answer+=chr((ord(i)-ord('A')+n)%26+ord('A'))
elif i.islower():
answer+=chr((ord(i)-ord('a')+n)%26+ord('a'))
elif i==" ":
answer+=" "
return answer