# include<stdio.h>
# include<stdlib.h>
int p,q,T;
int classchess[27][27];
int path[1000][2];int top=0;
int move[8][2]={{-2,-1},{-2,1},{-1,-2},{-1,2},{1,-2},{1,2},{2,-1},{2,1}};
int first;             //first==1 means if finded ,it is first!
int diff='A'-0;

void  DFS(int i,int j,int total)                 //i ,j 是将要访问的，total是有还多少没有访问(不包括将要的）？ 
{
      int k;
      int go_i,go_j;
      /*int x,y;
      int base;
      char dir=t+1;
       if(dir=='A'+q)
      dir='A';
      
      if(dir=='A'+q)
      base=2;
      else
      base=0;    
     int x,y;
     if(show==1)
     {
                /*/
     /*printf(" i j is %d %d\n",i,j);
     for(x=0;x<q;x++)
     {
        printf("\n");
        for(y=0;y<p;y++)
        printf("%d",classchess[x][y]);
     }
     printf("\n");
     //_sleep(200);
     */
      if(classchess[i][j]==0&&first==1)
      if(total==1)
      {
             
             path[top][0]=i+diff;
             path[top][1]=j+1;
             classchess[i][j]=1;
             top++;
            //printf("first is %d\n",first);
             if(first==1)
             {
               first=0;
               for(i=0;i<top;i++)
               {
                  printf("%c%d",path[i][0],path[i][1]);
               }
               printf("\n");
             }
             classchess[i][j]=0;
             top--;
      }
      else 
      {
           path[top][0]=i+diff;
           path[top][1]=j+1;
           top++;
           classchess[i][j]=1;
           for(k=0;k<8;k++)
           {
               //if(i==0&&j==0)
               //printf("move is %d%d\n",move[k][0],move[k][1]);
               go_i=i+move[k][0];go_j=j+move[k][1];
               if(go_i>=0&&go_i<q&&go_j>=0&&go_j<p)
               {
                  DFS(go_i,go_j,total-1);
               }
           }
           classchess[i][j]=0;
           top--;
      }
      
}
void processACase(int number)
{
     int i,j;
     scanf("%d %d",&p,&q);
     first=1;
     for(i=0;i<p;i++)
     for(j=0;j<q;j++)
     classchess[i][j]=0;
     
     printf("Scenario #%d:\n",number);
     
     DFS(0,0,p*q);
    
     if(first==1)
     {
      printf("impossible\n");
     }
     printf("\n");
}

int main()
{
    int i;
    scanf("%d",&T);
    for(i=0;i<T;i++)
    processACase(i+1);
}