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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int k = sc.nextInt();
        Cosme[] cosmes = new Cosme[n];
        for (int i = 0; i < n; i++) {
            cosmes[i] = new Cosme(i, sc.nextInt());
        }
        for (int i = 0; i < n; i++) {
            cosmes[i].b = sc.nextInt();
        }
        Arrays.sort(cosmes);
        char[] ans = new char[n];
        for (int i = 0; i < n; i++) {
            if (i < k) {
                ans[cosmes[i].idx] = 'A';
            } else {
                ans[cosmes[i].idx] = 'B';
            }
        } 
        System.out.println(ans);
    }
    
    static class Cosme implements Comparable<Cosme> {
        int idx;
        long a;
        long b;
        
        public Cosme(int idx, long a) {
            this.idx = idx;
            this.a = a;
        } 
        
        public int compareTo(Cosme another) {
            if (a - b == another.a - another.b) {
                return 0;
            } else if (a - b > another.a - another.b) {
                return -1;
            } else {
                return 1;
            }
        }
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public String nextLine() throws Exception {
        return br.readLine();
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}