#include "stdio.h"

main()
{
 FILE *fp1,*fp2;
 int ant_inst;
 int ant_lag,ant_kamp;
 int l,k,i,j;
 char lag1,lag2;
 int taperfor[28][28];
 int vinner,taper;
 int best;
 int plass[29];
 int nocycle;



 fp1 = fopen("rank.in","r");
 fp2 = fopen("rank.out","w");

 fscanf(fp1,"%d",&ant_inst);

 for(i=1;i<=ant_inst;i++)
 {
  fscanf(fp1,"%d %d \n",&ant_lag,&ant_kamp);

  for(j=1;j<=ant_lag;j++)
    for(k=1;k<=ant_lag;k++)
      taperfor[j][k] = 0;

  for(j=1;j<=ant_kamp;j++)
  {
   fscanf(fp1,"%c %c \n ",&lag1,&lag2);
   vinner = (int) (lag1 - 'A' + 1);
   taper = (int) (lag2 - 'A' + 1);
   taperfor[taper][vinner] = 1;
  }

  nocycle = 1;


  for(j=1;j<=ant_lag;j++)
  {
   best = 0;
   k=1;
   while ((k<= ant_lag) && (best==0))
   {
    best = k;
    for(l=1;l<=ant_lag;l++)
      if (taperfor[k][l] == 1)
        best = 0;
    k++;
   }

   if (best != 0) {
     plass[j] = best;
     for(l=1;l<=ant_lag;l++)
       taperfor[l][best] = 0;
     taperfor[best][best] = 1;
   }

   if (best == 0) {
     nocycle = 0;
   }
  }

  if (nocycle) {
    for(l=1;l<=ant_lag;l++)
      if (l==ant_lag)
        fprintf(fp2,"%c",plass[l] +'A' - 1);
      else
        fprintf(fp2,"%c ",plass[l] +'A' - 1);
    fprintf(fp2,"\n");
  }
  else
    fprintf(fp2,"No legal ranking possible\n");
 
 }
 
  fclose(fp2);

}