#include <bits/stdc++.h>
#define F(i,x,y) for(int i=(x);i<=(y);i++)
#define DF(i,x,y) for(int i=(x);i>=(y);i--)
#define ms(x,y) memset(x,y,sizeof(x))
#define SZ(x) (int)x.size()-1
#define all(x) x.begin(),x.end()
#define pb push_back
using namespace std;
typedef long long LL;
typedef unsigned long long ull;
typedef pair<int,int> pii;
template<typename T> void chkmax(T &x,T y){ x=max(x,y);}
template<typename T> void chkmin(T &x,T y){ x=min(x,y);}
template<typename T> void read(T &FF){
    FF=0;int RR=1;char ch=getchar();
    for(;!isdigit(ch);ch=getchar()) if(ch=='-') RR=-1;
    for(;isdigit(ch);ch=getchar()) FF=(FF<<1)+(FF<<3)+ch-48;
    FF*=RR;
}
int c[4];
int ord[4];
int fx[4][2]={{0,1},{0,-1},{-1,0},{1,0}};
char dy[4]={'U','D','L','R'};
void work(){
    int mx,my;cin>>mx>>my;
    string opt;cin>>opt;
    ms(c,0);
    F(i,0,SZ(opt)){
        if(opt[i]=='U') c[0]++;
        if(opt[i]=='D') c[1]++;
        if(opt[i]=='L') c[2]++;
        if(opt[i]=='R') c[3]++;
    }
    int tx=c[3]-c[2],ty=c[0]-c[1];
    if(tx==mx&&ty==my){ cout<<"Impossible"<<'\n';return;}
    if(!mx&&!my){ cout<<"Impossible"<<'\n';return;}
    bool fl=0;
    if(my==ty){
        fl=0;
        if(!my) fl=1;
    } 
    else if(mx==tx){
        fl=1;
        if(!mx) fl=0;
    }
    else fl=0;
    if(!fl){
        if(ty>=my) ord[0]=3,ord[2]=2;
        else ord[0]=2,ord[2]=3;
        if(tx>=mx) ord[1]=0,ord[3]=1;
        else ord[1]=1,ord[3]=0;
    }
    else{
        if(tx>=mx) ord[0]=0,ord[2]=1;
        else ord[0]=1,ord[2]=0;
        if(ty>=my) ord[1]=3,ord[3]=2;
        else ord[1]=2,ord[3]=3;
    }
    int x=0,y=0;
    F(i,0,3)
        F(j,1,c[ord[i]]){
            x+=fx[ord[i]][0],y+=fx[ord[i]][1];
            if(x==mx&&y==my){ cout<<"Impossible"<<'\n';return;}
        }
    F(i,0,3) F(j,1,c[ord[i]]) cout<<dy[ord[i]];
    cout<<'\n';
}
int main(){
    int T;cin>>T;
    while(T--) work();    
    return 0;
}