#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 100005
using namespace std;
int T,ax,ay,n,a[maxn]; char s[maxn]; int p[5],num[5];
void print(){
	for(int i=1;i<=4;i++){
		if(p[i]==1) for(int j=1;j<=a[1];j++) printf("U");
		if(p[i]==2) for(int j=1;j<=a[2];j++) printf("D");
		if(p[i]==3) for(int j=1;j<=a[3];j++) printf("L");
		if(p[i]==4) for(int j=1;j<=a[4];j++) printf("R");
	} printf("\n");
}
int main(){
	scanf("%d",&T); while(T--){
		scanf("%d%d%s",&ax,&ay,s+1); a[1]=a[2]=a[3]=a[4]=0; n=strlen(s+1);
		for(int i=1;i<=n;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 ifans=0; do{
			int x=0,y=0; bool flag=0;
			for(int i=1;i<=4;i++){
				int nx=x,ny=y; if(p[i]==1) ny+=a[1],flag|=(ax==nx&&ay>=y&&ay<=ny);
				else if(p[i]==2) ny-=a[2],flag|=(ax==nx&&ay>=ny&&ay<=y);
				else if(p[i]==3) nx-=a[3],flag|=(ay==ny&&ax>=nx&&ax<=x);
				else nx+=a[4],flag|=(ay==ny&&ax>=x&&ax<=nx); x=nx; y=ny;
			} if(!flag){print(); ifans=1; break;}
		}while(next_permutation(p+1,p+5)); if(ifans==0) printf("Impossible\n");
	} return 0;
}