#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define endl "\n"
#define FASTIO ios::sync_with_stdio(false);cin.tie(0),cout.tie(0);
char a[5]={'0','L','R','U','D'};
int b[5]={0,-1,+1,+1,-1};
void solve()
{
    int dx,dy;cin>>dx>>dy;
    int sx=0,sy=0,ex=0,ey=0;
    string s;cin>>s;
    int x=0,y=0;
    int n=s.size();
    map<char,int>mp;
    for(int i=0;i<n;i++)
    {
        mp[s[i]]++;
        if(s[i]=='U')
        y++;
        else if(s[i]=='D')
        y--;
        else if(s[i]=='L')
        x--;
        else
        x++;
    }
    if(dx==0&&dy==0||x==dx&&y==dy)
    {
        cout<<"Impossible"<<endl;
        return;
    }
    for(int i=1;i<=4;i++)
    {
        for(int j=1;j<=4;j++)
        {
            for(int k=1;k<=4;k++)
            {
                for(int z=1;z<=4;z++)
                {
                    if(i!=j&&i!=k&&i!=z&&j!=k&&j!=z&&k!=z)
                    {
                        sx=0,sy=0,ex=0,ey=0;
                        if(i<3)
                        ex+=mp[a[i]]*b[i];
                        else 
                        ey+=mp[a[i]]*b[i];
                        //cout<<sx<<" "<<sy<<endl;
                        //cout<<ex<<" "<<ey<<endl;
                        if((ex<=dx&&dx<=sx&&dy==ey&&i<3)||(sx<=dx&&dx<=ex&&dy==ey&&i<3)||(i>=3&&dx==ex&&dy>=sy&&dy<=ey)||(i>=3&&dx==ex&&dy>=ey&&dy<=sy))
                        {
                            continue;
                        }
                        sx=ex,sy=ey;

                        if(j<3)
                        ex+=mp[a[j]]*b[j];
                        else 
                        ey+=mp[a[j]]*b[j];
                        if((ex<=dx&&dx<=sx&&dy==ey&&j<3)||(ex<=dx&&dx<=sx&&dy==ey&&j<3)||(j>=3&&dx==ex&&dy>=sy&&dy<=ey)||(j>=3&&dx==ex&&dy>=ey&&dy<=sy))
                        {
                            continue;
                        }
                        sx=ex,sy=ey;

                        if(k<3)
                        ex+=mp[a[k]]*b[k];
                        else 
                        ey+=mp[a[k]]*b[k];
                        if((ex<=dx&&dx<=sx&&dy==ey&&k<3)||(sx<=dx&&dx<=ex&&dy==ey&&k<3)||(k>=3&&dx==ex&&dy>=sy&&dy<=ey)||(k>=3&&dx==ex&&dy>=ey&&dy<=sy))
                        {
                            continue;
                        }
                        sx=ex,sy=ey;

                        if(z<3)
                        ex+=mp[a[z]]*b[z];
                        else 
                        ey+=mp[a[z]]*b[z];
                        if((ex<=dx&&dx<=sx&&dy==ey&&z<3)||(sx<=dx&&dx<=ex&&dy==ey&&z<3)||(z>=3&&dx==ex&&dy>=sy&&dy<=ey)||(z>=3&&dx==ex&&dy>=ey&&dy<=sy))
                        {
                            continue;
                        }
                        for(int o=1;o<=mp[a[i]];o++)
                        cout<<a[i];
                        for(int o=1;o<=mp[a[j]];o++)
                        cout<<a[j];
                        for(int o=1;o<=mp[a[k]];o++)
                        cout<<a[k];
                        for(int o=1;o<=mp[a[z]];o++)
                        cout<<a[z];
                        cout<<endl;
                        return;
                    }
                }
            }
        }
    }
    cout<<"Impossible"<<endl;  
}

signed main()
{
    FASTIO;
    int t;cin>>t;
    while(t--)
    solve();
}