D

#include<iostream>
#include<vector>
#include <functional>
#include<string>
#include<algorithm>
#include <tuple>
#include<random>
#include <iomanip>
#include<set>
using namespace std;
using ll = unsigned long   long;
int gcd(int a, int b) {
    return b ? gcd(b, a % b) : a;
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, m;
    cin >> n >> m;
    string s = "", u = "";
    int k = gcd(n, m);
    if (k == 1)cout << "NO";
    else {
        cout << "YES" << '\n';
        for (int j = 2; j <= k; ++j) {
            if (n % j == 0 && m % j == 0) {
                for (int i = 0; i < m; ++i) {
                    if (!((i / j) % 2))s += 'B';
                    else s += 'X';
                }
                for (char i : s) {
                    if (i == 'B')
                        u += 'X';
                    else u += 'B';
                }
                for (int i = 0; i < n; ++i) {
                    if (!((i / j) % 2))
                        cout << s;
                    else
                        cout << u;
                    if (i != n - 1)cout << '\n';
                }
                break;
            }
        }
    }
}