def caesarCipher(s, k):
    res=""
    for i in range(len(s)):
        small, ch = check('a','z', s, i, k)
        if not small:
            big, ch = check('A', 'Z', s, i, k)
        res+=ch
    return res

def check(start, end, s, i,  k):
    n = ord(end)-ord(start)+1
    ch = s[i]
    if ord(start) <= ord(ch) <= ord(end):
        i = ord(ch) - ord(start)
        new_i = (i + k) % n
        return True, chr(ord(start) + new_i)
    return False, ch