#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <math.h>
#define REP(i, n) for (ll i = 0; i < n; i++)
#define REP1(i, n) for (ll i = 1; i <= n; i++)
#define RREP(i, n) for (ll i = n - 1; i >= 0; i--)
#define RREP1(i, n) for (ll i = n; i >= 1; i--)
#define FOR(i, a, b, c) for (ll i = a; i <= b; i += c)
#define RFOR(i, a, b, c) for (ll i = a; i >= b; i -= c)
#define MAX(a, b) (a > b ? a : b)
#define MIN(a, b) (a < b ? a : b)
#define INF 1145141919
typedef long long ll;

int n, d;

int main() {
    scanf("%d %d", &n, &d);    
    REP(i, n + 1) REP(j, n - i) {
        int k = n - i - j;
        if (j + k * 2 == d) {
            REP(t, j) putchar('A');
            REP(t, k) putchar('B');
            REP(t, i) putchar('C');
            return 0;
        }
    }
    return 1;
}