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();
        Product[] products = new Product[n];
        for (int i = 0; i < n; i++) {
            products[i] = new Product(i, sc.nextInt());
        }
        for (int i = 0; i < n; i++) {
            products[i].b = sc.nextInt();
        }
        Arrays.sort(products);
        for (int i = 0; i < k; i++) {
            products[i].isA = true;
        }
        char[] ans = new char[n];
        for (Product x : products) {
            if (x.isA) {
                ans[x.idx] = 'A';
            } else {
                ans[x.idx] = 'B';
            }
        }
        System.out.println(ans);
    }
    
    static class Product implements Comparable<Product> {
        int idx;
        int a;
        int b;
        boolean isA;
        
        public Product(int idx, int a) {
            this.idx = idx;
            this.a = a;
        }
        
        public int compareTo(Product another) {
            if (b - a == another.b - another.a) {
                return 0;
            } else if (b - a < another.b - another.a) {
                return -1;
            } else {
                return 1;
            }
        }
    }
}
    
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}