int i,j,k,l,m,n,ii;
char sym;
char input[100];
char stack[100];
int spoint=0;
out(){
  for(ii=0;ii<=spoint;ii++)printf("%c ",stack[ii]);
  for(ii=spoint+1;ii<=5;ii++)printf("%c ",' ');
  for(ii=1;ii<=i-1;ii++)printf("%c ",' ');
  for(ii=i;ii<=n;ii++)printf("%c ",input[ii]);
  for(ii=1;ii<=3;ii++)printf("%c ",' ');
}
push(char x){
  spoint++; stack[spoint]=x;
  out(); 
}
pop(){spoint--; out();}
error(int i){printf("error number %d\n",i);}
getsym(){
  if(i!=0)printf("consume %c ",sym); getchar();
  i++; sym=input[i]; out(); 
}
S(){
  printf("enter S"); getchar();
  push('S');
  if(sym=='a'){getsym(); T(); S();}
  else if(sym=='c')getsym();
  else error(1);
  printf("exit from S"); getchar();
  pop();
}
T(){
  printf("enter T"); getchar();
  push('T');
  if(sym=='b'){getsym(); S(); T();}
  else if(sym=='c')getsym();
  else error(2);
  printf("exit from T"); getchar();
  pop();
}
main(){
  printf("input n "); scanf("%d", &n); getchar();
  for(ii=1;ii<=n;ii++)scanf("%c",&input[ii]);       
  for(ii=1;ii<=n;ii++)printf("%c ",input[ii]);    
  printf("\n");
  getchar();
  i=0; getsym();
  S();
  if(spoint==0)printf("accept\n");
          else { error(3); printf("reject\n");}
}
/* error 1: a or c expected
   error 2: b or c expected
   error 3: ! expected
*/