#include <iostream>
#include <iomanip>
#include <vector>
using namespace std;


char matrix[4][4] = {0};
int nx[] = {1, 0, -1, 0};
int ny[] = {0, 1, 0, -1};
char smb[] = {'R', 'D', 'L', 'U'};
bool used[4][4] = {0};


int mind = 0;
vector<char> path;

bool dfs(int i, int j)
{

    if(path.size() > mind && i == 3 && j == 3)
    {
        for (int s = 0; s < path.size(); ++s)
        {
            cout << path[s];
        }
        path.clear();
        cout << endl;
        return 1;
    }

    for(int m = 0; m < 4; ++m)
    {
        if (i + ny[m] < 0 || i + ny[m] > 3 || j + nx[m] < 0 || j + nx[m] > 3 || matrix[i + ny[m]][j + nx[m]] == '#')
            continue;
        path.push_back(smb[m]);
        matrix[i + ny[m]][j + nx[m]] = '#';
        if (dfs(i + ny[m], j + nx[m]))
        {
            return 1;
        }
        matrix[i + ny[m]][j + nx[m]] = '.';
        path.pop_back();
    }
   
    return 0;
}


int main()
{
    freopen("input.txt", "r", stdin);
    //freopen("nsp.in", "r", stdin);
    //freopen("nsp.out", "w", stdout);

    char symb;
    for(;;)
    {
        for (int i = 0; i < 4; ++i)
        {
            for (int j = 0; j < 4; ++j)
            {
                cin >> matrix[i][j];                
            }
        }
        int dp[4][4] = {0};
        for(int i = 0; i < 4; ++i)
            for(int j = 0; j < 4; ++j)
                dp[i][j] = 1000;
        dp[0][0] = 0;
        dp[3][3] = 1111;
        for (int i = 0; i < 4; ++i)
        {
            for (int j = 0; j < 4; ++j)
            {
                if (i > 0 && matrix[i - 1][j] != '#')
                    dp[i][j] = min(dp[i][j], dp[i - 1][j] + 1);   
                if (j > 0 && matrix[i][j - 1] != '#')
                    dp[i][j] = min(dp[i][j], dp[i][j - 1] + 1);
            }
        }
        if (dp[3][3] == 1111 )
        {
            cout << -1 << endl;           
        }
        
        mind = dp[3][3];
        
        matrix[0][0] = '#';
        if (dfs(0, 0)  == 0)
        {
            cout << -1 << endl;
        }
        if (cin >> symb)
        {
            cin >> symb >> symb >> symb;
        }
        else
        {
            break;
        }

    } 

    


    return 0;
}