#include<bits/stdc++.h>
using namespace std;
#define int long long

int a[6];

void solve()
{
	int x,y,u,d,l,r;
	u = d = l = r = 0;
	string s;
	//memset(a,0,sizeof a);
	for(int i = 1;i <= 4;i++) {
		a[i] = i;
	}
	bool f = false;

	cin >> x >> y;
	cin >> s;
	if(x == 0 && y == 0) {
		cout << "Impossible" << endl;
		return;
	}
	for(int i = 0;i < s.size();i++) {
		if(s[i] == 'U') {
			u++;
		}
		if(s[i] == 'D') {
			d++;
		}
		if(s[i] == 'R') {
			r++;
		}
		if(s[i] == 'L') {
			l++;
		}
	}
    if(x == r+l && y == u+d) {
		cout << "Impossible" << endl;
		return;
	}
	while(true) {
		int xx = 0,yy = 0;
		bool flag = true;
		for(int i = 1;i <= 4;i++) {
			if(a[i] == 1 && xx == x && y >= yy && y <= yy + u) {
				flag = false;
				break;
			}
			if(a[i] == 2 && xx == x && y >= yy - d && y <= yy) {
				flag = false;
				break;
			}
			if(a[i] == 3 && yy == y && x >= xx - l && x <= xx) {
				flag = false;
				break;
			}
			if(a[i] == 4 && yy == y && y <= xx + r && x >= xx) {
				flag = false;
				break;
			}
			if(a[i] == 1) {
				yy += u;
			} else if(a[i] == 2) {
				yy -= d;
			} else if(a[i] == 3) {
				xx -= l;
			} else if(a[i] == 4) {
				xx += r;
			}
		}
		if(flag) {
			for(int i = 1;i <= 4;i++) {
				if(a[i] == 1) {
					for(int j = 1;j <= u;j++){
						cout<<"U";
					}
				}
				if(a[i] == 2) {
					for(int j = 1;j <= d;j++){
						cout<<"D";
					}
				}
				if(a[i] == 3) {
					for(int j = 1;j <= l;j++){
						cout<<"L";
					}
				}
				if(a[i] == 4){
					for(int j = 1;j <= r;j++){
						cout<<"R";
					}
				}
			}
			cout << endl;
			f = true;
			break;
		}
		if(!next_permutation(a + 1,a + 5)) {
			break;
		}
	}
	if(!f) {
		cout << "Impossible" << endl;
		return;
	}
	return;

}


signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);

	int T = 1;
	cin>>T;
	while(T--)
	{
		solve();
	}
	return 0;
}