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 { int idx; int a; int b; public Cosme(int idx, int a) { this.idx = idx; this.a = a; } public int compareTo(Cosme 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(""); 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(); } }