#include<bits/stdc++.h>
#define fo(s) freopen(s".in","r",stdin),freopen(s".out","w",stdout)
#define Ts template<typename Ty,typename... Ar>
#define Tp template<typename Ty>
#define isdigit(c) ((c)>='0'&&(c)<='9')
#define ll long long
#define RS register
#define gc getchar
#define pc putchar
#define I inline
using namespace std;
Tp I Ty wmax(Ty a,Ty b){return a>=b? a:b;}
Tp I Ty wmin(Ty a,Ty b){return a<=b? a:b;}
namespace WrongIO
{
	Tp I void read(Ty &x){x=0;Ty opt=1;char c=gc();while(!isdigit(c)&&c!='-')c=gc();if(c=='-')opt=-1,c=gc();while(isdigit(c))x=(x<<3)+(x<<1),x+=c-'0',c=gc();x*=opt;return;}
	Tp I void write(Ty x){short OI_USE[50],OI_top=0;if(x<=0) if(x==0)pc('0');else pc('-'),x*=-1;while(x)OI_USE[++OI_top]=x%10,x/=10;while(OI_top--)pc(OI_USE[OI_top+1]+'0');return;}
    I void writec(char c[]){int len=strlen(c);for(int i=0;i<len;i++)pc(c[i]);}
    I void writes(string s){int len=s.length();for(int i=0;i<len;i++)pc(s[i]);}
    I void readc(char &c,int l,int r){c=gc(); while(c!=EOF&&(c<l||c>r)) c=gc();}
    I void readc(char &c,char val){c=gc();while(c!=EOF&&c!=val) c=gc();}
    I void readc(char val){char c;c=gc();while(c!=EOF&&c!=val) c=gc();}
    I void readls(string &s){char c=gc();while(c!='\n') s.push_back(c),c=gc();}
    Ts I void read(Ty &x,Ar &...y) {read(x),read(y...);}
} using namespace WrongIO;
ll T,mx,my,len;
ll dx[4]={0,0,-1,1},dy[4]={1,-1,0,0},g[4];
ll sx[100050];
bool flag=1;
char mp[4]={'U','D','L','R'};
void dfs(ll x,ll y,ll dep)
{
	if(flag==0) return;
	if(x==mx&&y==my) return;
	if(dep==len+1)
	{
		for(int i=1;i<=len;i++)
		pc(mp[sx[i]]);
		flag=0; pc('\n');
		return;
	}
	for(int i=0;i<4;i++)
	{
		if(g[i]==0) continue;
		g[i]-=1; sx[dep]=i;
		ll tx=x+dx[i],ty=y+dy[i];
		dfs(tx,ty,dep+1);
		if(flag==0) return;
		g[i]+=1;
	}
}
int main()
{
	read(T);
	while(T--)
	{
		flag=1;
		string s;
		cin>>mx>>my>>s;
		len=s.length();
		memset(g,0,sizeof(g));
		for(int i=0;i<len;i++)
		{
			if(s[i]=='U') g[0]++;
			if(s[i]=='D') g[1]++;
			if(s[i]=='L') g[2]++;
			if(s[i]=='R') g[3]++;
		}
		ll x=g[3]-g[2],y=g[0]-g[1];
		if(mx==x&&my==y)
		{
			writes("Impossible\n");
			continue;
		}
		if((g[0]==0)+(g[1]==0)+(g[2]==0)+(g[3]==0)==3)
		{
			bool flag=0;
			if(g[0]!=0&&mx==0&&0<=my&&my<=g[0]) flag=1;
			if(g[1]!=0&&mx==0&&-g[1]<=my&&my<=0) flag=1;
			if(g[2]!=0&&my==0&&-g[2]<=mx&&mx<=0) flag=1;
			if(g[3]!=0&&my==0&&0<=mx&&mx<=g[3]) flag=1;
			if(flag)
			{
				writes("Impossible\n");
				continue;
			}
		}
		dfs(0,0,1);
	}
}