#include <algorithm>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <cstring>
#include <ctime>
#include <cassert>
using namespace std;
typedef long long LL;
#define FOR(k,a,b) for(int k(a); k < (b); ++k)
#define FORD(k,a,b) for(int k(b-1); k >= (a); --k)
#define REP(k,a) for(int k=0; k < (a); ++k)
#define ABS(a) ((a)>0?(a):-(a))

char c[1002][1002];
char ans[2000000];
int N,T;

char dirc[4]={'U','D','R','L'};
int dir[4][2]={{-1,0},{1,0},{0,1},{0,-1}};

string findroute(const pair<int,int>& from, const pair<int,int>& to)
{
	vector<pair<pair<int,int>, string> > q;
	q.push_back(make_pair(from,string()));
	REP(i,q.size())
	{
		pair<int,int> actpos = q[i].first;
		string actstr = q[i].second;
		int row = actpos.first;
		int col = actpos.second;
		REP(j,4)
		{
			int nr = row + dir[j][0];
			int nc = col + dir[j][1];
			if(nr>=0 && nr<N && nc>=0 && nc<N && c[nr][nc]!='#')
			{
				pair<int,int> npos = make_pair(nr,nc);
				string ns = actstr + dirc[j];
				if(npos == to)
					return ns;
				q.push_back(make_pair(npos,ns));
			}
		}
	}
	return string();
}

int main( int argc, char* argv[] ) {
#ifdef HOME
	freopen("in.txt","r",stdin);
	freopen("out.txt","wb",stdout);
#endif
	scanf("%d",&T);
	
	while(T--)
	{
		scanf("%d",&N);
		REP(i,N)
			scanf("%s",c[i]);
		vector<string> dr((N+1)/2);
		vector<pair<int,int> > start((N+1)/2), finish((N+1)/2);
		REP(r, (N+1)/2)
		{
			vector<vector<bool> > used(2,vector<bool> (N,0));
			int row1=2*r;
			int row2=2*r+1;
			if(row2==N)
			{
				row2-=2;
				swap(row1,row2);
			}
			int row = row1;
			int col = 0;
			if(c[row][col]=='#') ++row;
			start[r]=make_pair(row,col);
			used[row-row1][col]=1;
			while(1)
			{
				int otherrow = row == row1? row2 : row1;
				//try to step up,down if it is not used or forbidden
				if(c[otherrow][col]=='.' && !used[otherrow-row1][col])
				{
					//then step
					if(row==row1)
					{
						dr[r].push_back('D');
						++row;
					}
					else
					{
						dr[r].push_back('U');
						--row;
					}
					used[row-row1][col]=1;
				}
				else if(col+1<N && c[row][col+1]=='.')
				{
					//step right
					dr[r].push_back('R');
					++col;
					used[row-row1][col]=1;
				}
				else if(col+1<N)
				{
					//go back
					if(row==row1)
					{
						dr[r].push_back('D');
						++row;
					}
					else
					{
						dr[r].push_back('U');
						--row;
					}
				}
				else
				{
					finish[r]=make_pair(row,col);
					break;
				}

			}
		}
		int pos = 0, dir = 0;
		for(;pos<dr[0].length();++pos)
			ans[pos]=dr[0][pos];
		FOR(i,1,dr.size())
		{
			//connect i-1 finish with i
			dir = 1-dir;
			if(dir)
			{
				//connect i-1 finish with i finish
				string str = findroute(finish[i-1],finish[i]);
				REP(j,str.size())
				{
					ans[pos]= str[j];
					++pos;
				}
				//
				FORD(j,0,dr[i].size())
				{
					char& c = dr[i][j];
					switch(c)
					{
					case 'R':
						ans[pos]='L';
						break;
					case 'L':
						ans[pos]='R';
						break;
					case 'U':
						ans[pos]='D';
						break;
					case 'D':
						ans[pos]='U';
						break;
					default:
						assert(false);
					}
					++pos;
				}
			}
			else
			{
				//connect i-1 start with i start
				string str = findroute(start[i-1],start[i]);
				REP(j,str.size())
				{
					ans[pos]= str[j];
					++pos;
				}
				//
				REP(j,dr[i].size())
				{
					ans[pos]= dr[i][j];
					++pos;
				}
			}
		}
		ans[pos]=0;
		printf("%s\n",ans);
	}
	return 0;
}