#include<bits/stdc++.h>
const int N=1e3+10;
const int M=2e6+10;
#define int long long
typedef double db;
typedef long long ll;
using namespace std;
using pii = pair<int,int>;
#define up(i,a,b) for(int i=(a);i<=(b);++i)
#define down(i,a,b) for(int i=(a);i>=(b);--i)
#define puts(a) (cout<<a<<endl)
#define inf (0x7fffffff)
const int MOD=100003;
int mx,my;
int a[4] = {0,1,2,3};
int vis[4] = {0};
int dir[4][2] = {{0,1},{0,-1},{-1,0},{1,0}};
map<int,string>mp;

bool check(){
    int x = 0,y = 0;
    for(int i = 0;i < 4;i++){
        for(int j = 0;j < vis[a[i]];j++){
            x+=dir[a[i]][0];
            y+=dir[a[i]][1];
            if(x == mx&&y == my)
                return false;
        }
    }
    return true;
}

void solve(){
    mp[0] = 'U',mp[1] = 'D',mp[2] = 'L',mp[3] = 'R';
        cin >> mx >> my;
        string s;
        cin >> s;
        if((mx == 0&&my == 0)){
            cout << "Impossible"<<endl;
            return ;
        }
        int x = 0,y = 0;
        memset(vis,0,sizeof(vis));
        a[0] = 0,a[1] = 1,a[2] = 2,a[3] = 3;
        for(int i = 0;i < s.size();i++){
            if(s[i] == 'U'){
                vis[0]++;
                y++;
            }
            if(s[i] == 'D'){
                vis[1]++;
                y--;
            }
            if(s[i] == 'L'){
                vis[2]++;
                x--;
            }
            if(s[i] == 'R'){
                vis[3]++;
                x++;
            }
        }


        if(x == mx&&y == my){
            cout << "Impossible"<<endl;
            return ;
        }
        bool finds = 0;
        bool flag=1;
        while(flag){

            if(check()){
                finds = 1;
                for(int i = 0;i < 4;i++){
                    for(int j = 0;j< vis[a[i]];j++)
                        cout<<mp[a[i]];
                }
                cout<<endl;
                break;
            }
            if(!next_permutation(a,a+4))
                flag=0;
        }

        if(!finds)
            cout << "Impossible\n";

}


signed main() {
int T;
ios::sync_with_stdio(false);
cin.tie(0),cout.tie(0);
    T=1;
    cin>>T;
    while(T--)
    solve();
    return 0;
}