Shared code

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

// number of prime numbers less then or equal to x are  -->  x/ln(x)
public class b {
    static FastScanner sc;
    static PrintWriter pw;

    static class FastScanner {
        InputStreamReader is;
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            is = new InputStreamReader(System.in);
            br = new BufferedReader(is);
        }

        String next() throws Exception {
            while (st == null || !st.hasMoreElements())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

        int nextInt() throws Exception {
            return Integer.parseInt(next());
        }

        long nextLong() throws Exception {
            return Long.parseLong(next());
        }

        int[] readArray(int num) throws Exception {
            int arr[] = new int[num];
            for (int i = 0; i < num; i++)
                arr[i] = nextInt();
            return arr;
        }

        String nextLine() throws Exception {
            return br.readLine();
        }
    }

    public static boolean power_of_two(int a) {
        if ((a & (a - 1)) == 0) {
            return true;
        }
        return false;
    }

    static boolean PS(double x) {
        if (x >= 0) {
            double i = Math.sqrt(x);
            if (i % 1 != 0) {
                return false;
            }
            return ((i * i) == x);
        }
        return false;
    }

    public static int[] ia(int n) {
        int ar[] = new int[n];
        return ar;
    }

    public static long[] la(int n) {
        long ar[] = new long[n];
        return ar;
    }

    public static void print(int ans, int t) {
        System.out.println("Case" + " " + "#" + t + ":" + " " + ans);
    }

    static long mod = 1000000007;
    static int max = Integer.MIN_VALUE;
    static int min = Integer.MAX_VALUE;

    // **** M A I N C O D E ****
    static class pair {
        int i;
        int j;

        String psf;

        pair(int i, int j, String psf) {
            this.i = i;
            this.j = j;

            this.psf = psf;
        }
    }

    public static void main(String args[]) throws java.lang.Exception {
        StringBuilder s = new StringBuilder();
        sc = new FastScanner();
        pw = new PrintWriter(System.out);
        int n = sc.nextInt();
        int m = sc.nextInt();
        char ar[][] = new char[n][];
        boolean ck[][] = new boolean[n][m];
        for (int i = 0; i < n; i++) {
            ar[i] = sc.next().toCharArray();
        }
        ArrayDeque<pair> q = new ArrayDeque<>();
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (ar[i][j] == 'A') {
                    q.add(new pair(i, j, ""));
                    break;
                }
            }
        }
        String ans = "";
        while (q.size() > 0) {
            pair h = q.remove();
            if (h.i < 0 || h.j < 0 || h.i >= n || h.j >= m || ck[h.i][h.j] || ar[h.i][h.j] == '#') {
                continue;
            }
            if (ar[h.i][h.j] == 'B') {
                ans = h.psf;
                break;
            }
            ck[h.i][h.j] = true;

            // System.out.println(h.psf);
            int i = h.i;
            int j = h.j;
            String psf = h.psf;
            q.add(new pair(i + 1, j, psf + 'D'));
            q.add(new pair(i - 1, j, psf + 'U'));

            q.add(new pair(i, j - 1, psf + 'L'));

            q.add(new pair(i, j + 1, psf + 'R'));

        }
        s.append(ans.length() == 0 ? "NO" : "YES" + "\n" + ans.length() + "\n" + ans);
        pw.print(s);
        pw.close();
    }
}