#include "bits/stdc++.h"

using namespace std;



#define FOR(i,a,b) for(int i=a;i<b;i++)
#define For(i,b) FOR(i,0,b)
#define pi pair<int,int>
#define f first
#define s second


const int MX=105;
int grid[MX][MX];
int dist[MX][MX];
int from[MX][MX];
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};
char dir[4]={'U','D','L','R'};//opposite of dx,dy

int main(){
	int n,m;cin>>n>>m;
	int sx,sy,fx,fy;
	For(i,n){
		string S;cin>>S;
		For(j,m){
			if(S[j]=='#')grid[i][j]=0;
			else grid[i][j]=1;
			if(S[j]=='S')sx=i,sy=j;
			if(S[j]=='F')fx=i,fy=j;
		}
	}
	For(i,n)For(j,m)dist[i][j]=1e9;

	//BFS from end point
	queue<pi> q;
	q.push({fx,fy});
	dist[fx][fy]=0;
	while((int)q.size()){
		pi x=q.front();q.pop();
		For(k,4){
			int nx=x.f+dx[k],ny=x.s+dy[k];
			if(grid[nx][ny]==1){
				if(dist[x.f][x.s]+1<dist[nx][ny]){
					dist[nx][ny]=dist[x.f][x.s]+1;
					from[nx][ny]=k;
					q.push({nx,ny});
				}
			}
		}
	}

	//backtracking to find optimal path
	string ret="";
	int tmpX=sx,tmpY=sy;
	while(tmpX!=fx || tmpY!=fy){
		int k=from[tmpX][tmpY];
		tmpX-=dx[k],tmpY-=dy[k];
		ret+=dir[k];
	}
	cout<<ret<<endl;
}