String alpha = "abcdefghijklmnopqrstuvwxyz";
        while(k > 26){
            k -= 26;
        }
        String route = alpha.substring(k, 26).concat(alpha.substring(0,k));
        Map<String,Integer> ls = new HashMap();
        Map<Integer,String> ls2 = new HashMap();

        int cout =  1;
        for(char c: alpha.toCharArray()){
            ls.put(String.valueOf(c),cout);
            ls2.put(cout, String.valueOf(route.charAt(cout-1)));
            
            System.out.println(String.valueOf(route.charAt(cout-1)));
            cout ++;
        }
        
        StringBuilder f = new StringBuilder();
        for(char c: s.toCharArray()){
            String cs = String.valueOf(c);
            if(alpha.contains(cs)){
                f.append(ls2.get(ls.get(cs)));
            } else if(alpha.contains(cs.toLowerCase())) {
                f.append(ls2.get(ls.get(cs.toLowerCase())).toUpperCase());
            } else {
                f.append(cs);
            }
        }
        
        return f.toString();