#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=200005;
int n,mx,my;
int a[5],p[5]; 
string s;
void print(){
	for(int i=1;i<=4;i++){
		if(p[i]==1) for(int j=1;j<=a[1];j++) cout<<'U';
		if(p[i]==2) for(int j=1;j<=a[2];j++)cout<<'D';
		if(p[i]==3) for(int j=1;j<=a[3];j++) cout<<'L';
		if(p[i]==4) for(int j=1;j<=a[4];j++)cout<<'R';
	} 
	cout<<endl;
}
void solve(){
	cin>>mx>>my>>s;
	memset(a,0,sizeof(a));
		for(int i=0;i<s.length();i++){
			if(s[i]=='U') a[1]++; 
			else if(s[i]=='D') a[2]++; 
			else if(s[i]=='L') a[3]++; 
			else a[4]++;
		} 	
		p[1]=1; p[2]=2; p[3]=3; p[4]=4; 
		
		bool k=0; 
		do{
			int x=0,y=0; bool f=0;
			for(int i=1;i<=4;i++){
				int nx=x,ny=y; 
				if(p[i]==1) ny+=a[1],f|=(mx==x&&y<=my&&my<=ny);
				else if(p[i]==2) ny-=a[2],f|=(mx==x&&ny<=my&&my<=y);
				else if(p[i]==3) nx-=a[3],f|=(my==y&&nx<=mx&&mx<=x);
				else nx+=a[4],f|=(my==y&&x<=mx&&mx<=nx); 
				x=nx; y=ny;
			} 
			if(!f){
				print();k=1; 
				break;
			}
		}while(next_permutation(p+1,p+5)); 
	
	if(k==0) cout<<"Impossible"<<endl;
	return;
}
signed main() {
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("in.txt","r",stdin);
	//freopen("out.txt","w",stdout);
	int T_case=1;
	cin>>T_case;
	while(T_case--){
		solve();
	}
    return 0;
}