#include <bits/stdc++.h>
using namespace std;

const int dx[4] = { +1, 0, -1, 0 };
const int dy[4] = { 0, +1, 0, -1 };
const string dirs = "DRUL";

char s[30][30];

int mp[30][30];
int E[410][4];

int dis[410][410];
int pre[410][410];

int main() {
	int n, m;
	cin >> n >> m;
	for (int x = 0; x < n; ++x) {
		cin >> s[x];
	}

	int V = 0;
	memset(mp, ~0, sizeof(mp));  // -1
	for (int x = 0; x < n; ++x) {
		for (int y = 0; y < m; ++y) {
			if (s[x][y] == '1') {
				mp[x][y] = V++;
			}
		}
	}
	for (int x = 0; x < n; ++x) {
		for (int y = 0; y < m; ++y) {
			int u = mp[x][y];
            if (u == -1) continue;
            for (int i = 0; i < 4; ++i) {
                auto [nx, ny] = pair(x + dx[i], y + dy[i]);
                E[u][i] = (0 <= nx && nx < n && 0 <= ny && ny < m && ~mp[nx][ny]) ? mp[nx][ny] : u;
            }
		}
	}

	queue<pair<int, int>> Q;
	memset(dis, ~0, sizeof(dis));
	memset(pre, ~0, sizeof(pre));
	for (int u = 0; u < V; ++u) {
		dis[u][u] = 0;
		Q.push({ u, u });
	}
	while (!Q.empty()) {
		auto [u, v] = Q.front();
        Q.pop();
		for (int dir = 0; dir < 4; ++dir) {
			for (auto nu : { u, E[u][dir ^ 2] }) {
				if (E[nu][dir] != u) continue;
                for (auto nv : {v, E[v][dir ^ 2]}) {
                    if (E[nv][dir] != v) continue;
                    if (dis[nu][nv] != -1) continue;
                    dis[nu][nv] = dis[u][v] + 1;
                    pre[nu][nv] = dir;
                    Q.push({ nu, nv });
                }
			}
		}
	}

	vector<int> us(V);
	for (int u = 0; u < V; ++u) {
		us[u] = u;
	}

	string ans;
	for (; us.size() > 1; ) {
		int mn = -1;
		int tu = -1, tv = -1;
		for (int i = 0; i < us.size(); ++i) {
			for (int j = i + 1; j < us.size(); ++j) {
				if (mn = max(mn, dis[us[i]][us[j]])) {
					tu = us[i];
					tv = us[j];
				}
			}
		}
        // cerr << tu << " " << tv << endl;
        // cerr << dis[tu][tv] << endl;
		for (int u = tu, v = tv; u != v; ) {
			const int dir = pre[u][v];
			ans += dirs[dir];
			u = E[u][dir];
			v = E[v][dir];
			for (int& w : us) {
				w = E[w][dir];
			}
		}
        //cerr << ans << endl;
		sort(us.begin(), us.end());
		us.erase(unique(us.begin(), us.end()), us.end());
	}

	cout << ans << endl;
	return 0;
}