package chelper;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;

import io.InputReader;
import io.OutputWriter;

public class C {
  char[] dirsOrderLabels = {'D', 'L', 'R', 'U'};
  int[][] dirsOrder = {
      {1, 0},  //D
      {0, -1}, //L
      {0, 1},  //R
      {-1, 0}, //U
  };

  public void solve(int testNumber, InputReader in, OutputWriter out) {
    int n = in.nextInt();
    int m = in.nextInt();
    int k = in.nextInt();

    int startX = -1;
    int startY = -1;

    boolean[][] map = new boolean[n][m];

    for (int i = 0; i < n; i++) {
      String s = in.nextLine();
      for (int j = 0; j < m; j++) {
        map[i][j] = s.charAt(j) != '*';
        if (s.charAt(j) == 'X') {
          startX = i;
          startY = j;
        }
      }
    }

    int[][] distances = new int[n][m];
    for (int i = 0; i < n; i++) {
      Arrays.fill(distances[i], Integer.MAX_VALUE);
    }

    Queue<int[]> queue = new LinkedList<>();
    queue.add(new int[]{startX, startY});
    distances[startX][startY] = 0;

    while (!queue.isEmpty()) {
      int[] posAr = queue.poll();
      int x = posAr[0];
      int y = posAr[1];

      for (int[] dir : dirsOrder) {
        int xx = x + dir[0];
        int yy = y + dir[1];

        if (xx < 0 || xx >= n || yy < 0 || yy >= m) {
          continue;
        }

        if (!map[xx][yy]) {
          continue;
        }

        if (distances[xx][yy] <= distances[x][y] + 1) {
          continue;
        }

        distances[xx][yy] = distances[x][y] + 1;
        queue.add(new int[]{xx, yy});
      }
    }

    StringBuilder answer = new StringBuilder();

    int x = startX;
    int y = startY;
    int timeLeft = k;

    while (timeLeft >= distances[x][y] && timeLeft > 0) {
      boolean ok = false;
      for (int i = 0; i < 4; i++) {
        int[] dir = dirsOrder[i];
        int xx = x + dir[0];
        int yy = y + dir[1];

        if (xx < 0 || xx >= n || yy < 0 || yy >= m) {
          continue;
        }

        if (!map[xx][yy]) {
          continue;
        }

        if (timeLeft == distances[x][y] && distances[xx][yy] >= distances[x][y]) {
          continue;
        }

        ok = true;
        x = xx;
        y = yy;
        timeLeft--;
        answer.append(dirsOrderLabels[i]);
        break;
      }

      if (!ok) {
        out.println("IMPOSSIBLE");
        return;
      }
    }

    if (timeLeft != 0 || x != startX || y != startY) {
      out.println("IMPOSSIBLE");
      return;
    }

    out.println(answer);
  }
}