/* Problem URL: https://cses.fi/problemset/task/1193 */

#include <bits/stdc++.h>

using namespace std;

#define V vector

#define rmin(a, b) a = min(a, b)
#define rmax(a, b) a = max(a, b)

#define rep(i, lim) for (int i = 0; i < (lim); i++)
#define nrep(i, s, lim) for (int i = s; i < (lim); i++)

#define repv(i, v) for (auto &i : (v))
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
#define sortv(v) sort(v.begin(), v.end())
#define all(v) (v).begin(), (v).end()

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;

using ll = long long;

using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;

template<class v>
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
    os << vec[0];
    for (size_t i = 1; i < vec.size(); i++) {
        os << ' ' << vec[i];
    }
    os << '\n';
    return os;
}

template<class v>
auto operator>>(istream &is, vector<v> &vec)->istream& {
    for (auto &i : vec) {
        is >> i;
    }
    return is;
}

template<class v>
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
    for (auto &i : vec) {
        os << i[0];
        for (size_t j = 1; j < i.size(); j++) {
            os << ' ' << i[j];
        }
        os << '\n';
    }
    return os;
}

template<class v>
auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
    for (auto &i : vec) {
        for (auto &j : i) {
            is >> j;
        }
    }
    return is;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m;
    cin >> n >> m;

    V<string> fds(n);
    cin >> fds;

    int is;
    int js;

    rep(i, n) {
        rep(j, m) {
            if (fds[i][j] == 'A') {
                is = i;
                js = j;
                goto leave;
            }
        }
    }

leave:

    string ans;
    auto bfs = [&](int i, int j) {
        queue<pair<int, int>> q;
        q.emplace(i, j);

        while (!q.empty()) {
            auto [i, j] = q.front();
            q.pop();

            int add[][3] = {{0, 1, 0}, {1, 0, 1}, {0, -1, 2}, {-1, 0, 3}};

            for (auto &k : add) {
                int id = i + k[0];
                int jd = j + k[1];

                if (id >= 0 && id < n && jd >= 0 && jd < m) {
                    if (fds[id][jd] == 'B') {
                        char var[] = {'R', 'D', 'L', 'U'};
                        ans.push_back(var[k[2]]);
                        return make_pair(i, j);
                    }

                    if (fds[id][jd] == '.') {
                        fds[id][jd] = k[2];
                        q.emplace(id, jd);
                    }
                }
            }
        }

        return make_pair(-1, -1);
    };

    auto [i, j] = bfs(is, js);

    if (i == -1) {
        cout << "NO\n";
        return 0;
    }

    cout << "YES\n";

    while (fds[i][j] != 'A') {
        switch(fds[i][j]) {
        case 0:
            ans.push_back('R');
            j--;
            break;
        case 1:
            ans.push_back('D');
            i--;
            break;
        case 2:
            ans.push_back('L');
            j++;
            break;
        case 3:
            ans.push_back('U');
            i++;
            break;
        }
    }

    reverse(all(ans));
    cout << ans.size() << '\n' << ans << '\n';
}