String

//package javaapplication1;



import java.util.*;
import java.io.*;


import java.io.*;

/**
 *
 * @author adahyvar
 */
public class JavaApplication1 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        
        IO io = new IO();
        
        
        
        string(io);
       
        io.close();
    }
    
    
    
    public static void string(IO io) {
        long luku = io.nextLong();
        String rivi = io.next();
        
        String vastaus = "";
        
        HashMap<Character, Integer> aakkoset = new HashMap();
        aakkoset.put('a', 0);
        aakkoset.put('b', 25);
        aakkoset.put('c', 24);
        aakkoset.put('d', 23);
        aakkoset.put('e', 22);
        aakkoset.put('f', 21);
        aakkoset.put('g', 20);
        aakkoset.put('h', 19);
        aakkoset.put('i', 18);
        aakkoset.put('j', 17);
        aakkoset.put('k', 16);
        aakkoset.put('l', 15);
        aakkoset.put('m', 14);
        aakkoset.put('n', 13);
        aakkoset.put('o', 12);
        aakkoset.put('p', 11);
        aakkoset.put('q', 10);
        aakkoset.put('r', 9);
        aakkoset.put('s', 8);
        aakkoset.put('t', 7);
        aakkoset.put('u', 6);
        aakkoset.put('v', 5);
        aakkoset.put('w', 4);
        aakkoset.put('x', 3);
        aakkoset.put('y', 2);
        aakkoset.put('z', 1);

        
        ArrayList<Character> merkit = new ArrayList();
        
        for (int i = 0; i < rivi.length() - 1; i++) {
            
            
            
            if (aakkoset.get(rivi.charAt(i)) <= luku && rivi.charAt(i) != 'a') {
                luku -= aakkoset.get(rivi.charAt(i));
                //vastaus += "a";
                merkit.add('a');
            } else {
                //vastaus += rivi.charAt(i);
                merkit.add(rivi.charAt(i));
            }
            
        }
        
        
        
        luku = luku%26;
        
        String kaikki = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
        
        for (int i = 0; i < kaikki.length(); i++) {
            if (rivi.charAt(rivi.length() - 1) == kaikki.charAt(i)) {
                //vastaus += kaikki.charAt((int)luku + i);
                merkit.add(kaikki.charAt((int)luku + i));
                break;
            }
        }
        
        for (Character character : merkit) {
            System.out.print(character);
        }
        
    }
    
    
//    If GCGC is more frequent, 
//            then output Maija, and if ATAT is more frequent, 
//            then output Kaaleppi. If they are both equally frequent, then output not sure.
    
    public static String kmer(IO io) {
        String dna = io.next();
        
        int m = 0;
        int k = 0;
        
        for (int i = 3; i < dna.length(); i++) {
            
            if (dna.charAt(i) == 'C') {
                if (dna.charAt(i-3) == 'G' && dna.charAt(i-2) == 'C' && dna.charAt(i-1) == 'G') {
                    m++;
                }
            }
            if (dna.charAt(i) == 'T') {
                if (dna.charAt(i-3) == 'A' && dna.charAt(i-2) == 'T' && dna.charAt(i-1) == 'A') {
                    k++;
                }
            }
            
        }
        
        if (m > k) {
            return "Maija";
        } else if (k > m) {
            return "Kaaleppi";
        } else {
            return "not sure";
        }
        
    }
    
    
    public static int blocks(IO io) {
        int b = io.nextInt();
        
        TreeSet<Long> tornit = new TreeSet();
        
        for (int i = 0; i < b; i++) {
            long luku = io.nextLong();

            if (tornit.ceiling(luku) != null) {
                tornit.remove(tornit.ceiling(luku));
            }
            
            tornit.add(luku);
        }
        
        return tornit.size();
    }
    
    
    
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED