> #include <iostream>
using namespace std;

int visit[10][10];
bool judge;
struct path {int x;int y;};
int next[8][2]={{-2,-1},{-2,1},{-1,-2},{-1,2},{1,-2},{1,2},{2,-1},{2,1}}; 
path result[64];
int num,latin;
void findpath(int i,int j,int Count)
{
	if(judge==1) return;
	int p,q;
	visit[i][j]=1;
	result[Count-1].x=i;
	result[Count-1].y=j;
	if(Count==num*latin)
	{
		judge=1;
		return;
	}
	for(int a=0;a<8;a++)
	{
		p=i+next[a][0];
		q=j+next[a][1];
		if(p<latin && p>=0 && q>=0 && q<num)
			if(visit[p][q]==0)
			{
				findpath(p,q,Count+1);
				if(judge) return;
				else{
					visit[i][j]=0;
				}
			}
	}
	return;
}
int main()
{
	int n;
	int a,b,c=1,d;
	cin>>n;
	while(c<=n)
	{
		judge=0;
	    for(a=0;a<10;a++)
		    for(b=0;b<10;b++)
		    	visit[a][b]=0;
		cin>>num>>latin;
		if(num*latin>26 || num*latin<1) continue;
		findpath(0,0,1);
		cout<<"Scenario #"<<c<<":"<<endl;
		if(!judge) cout<<"impossible";
		else for(d=0;d<num*latin;d++) cout<<char('A'+result[d].x)<<result[d].y+1;
		cout<<endl<<endl;
		c++;
	}
	return 0;
}