1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class slo {

    private static final String A = "a";
    private static final String B = "b";
    private static final String C = "c";
    private static final String NIE = "NIE";
    private static final List<String> LETTERS = Arrays.asList(A, B, C);

    private static int count = 0;

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int max_len = sc.nextInt();
        int elem = sc.nextInt();

        StringBuilder word = new StringBuilder();

        boolean found = false;

        for (String letter : LETTERS) {
            if (!found) {
                found = searchTree(1, max_len, elem, word, letter);
            }
        }

        if (!found) {
            System.out.println(NIE);
        }
    }

    private static boolean searchTree(int depth, int max_len, int elem, StringBuilder myWord, String letter) {

        myWord.append(letter);
        count++;
        if (elem == count) {
            System.out.println(myWord.toString());
            return true;
        }
        if (depth < max_len) {
            if (searchTree(depth + 1, max_len, elem, myWord, getLeft(letter))) {
                return true;
            }
            if (searchTree(depth + 1, max_len, elem, myWord, getRight(letter))) {
                return true;
            }
        }
        myWord.setLength(myWord.length() - 1);
        return false;
    }


    private static String getLeft(String letter) {
        switch (letter) {
            case A:
                return B;
            case B:
                return A;
            case C:
                return A;
            default:
                return "0";
        }
    }

    private static String getRight(String letter) {
        switch (letter) {
            case A:
                return C;
            case B:
                return C;
            case C:
                return B;
            default:
                return "0";
        }
    }
}