public static String caesarCipher(String s, int k) {
        // Write your code here
        StringBuffer sb = new StringBuffer();
        int dk = k % 26;
        
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            boolean upperAlpha = ('A' <= c && c <= 'Z') ? true : false;
            
            char minChar = (upperAlpha) ? 'A' : 'a';
            char maxChar = (upperAlpha) ? 'Z' : 'z';
            
            if (minChar <= c && c <= maxChar) {
                int encrypted = c + dk;
                if (encrypted > maxChar) {
                    encrypted = minChar + (encrypted - maxChar - 1);
                }
                sb.append((char)encrypted);                
            } 
            else {
                sb.append(s.charAt(i));
            }
        }
        
        return sb.toString();
    }