I show the correct answer but tell me WA. why?

I can tell you that it is very simple test but there some important things that must be forseen,so one of them is that when you write,for example, a,b:string; you must not read it like this readln(a,b); or read(a,b);
 you must write separately like this readln(a);
                                     readln(b);
So I will write my program for you :)

program amoc1446;
var a,b:array[1..1000] of string[200];
    i,n:integer;
begin
    readln(n);
    for i:=1 to n do
    begin
        readln(a[i]);
        readln(b[i]);
    end;

          writeln('Slytherin:');
  for i:=1 to n do
    if b[i]='Slytherin' then
      writeln(a[i]);
      writeln;

  writeln('Hufflepuff:');
  for i:=1 to n do
   if b[i]='Hufflepuff' then
     writeln(a[i]);
     writeln;

  writeln('Gryffindor:');
  for i:=1 to n do
    if b[i]='Gryffindor' then
      writeln(a[i]);
      writeln;
  writeln('Ravenclaw:');
  for i:=1 to n do
    if b[i]='Ravenclaw' then
      writeln(a[i]);

end.

I can tell you that it is very simple test but there are some important things that you must  forseen,so one of them is that when you write,for example, a,b:string; you must not read it like this readln(a,b); or read(a,b);
 you must write separately like this readln(a);
                                     readln(b);
So I will write my program for you :)

program amoc1446;
var a,b:array[1..1000] of string[200];
    i,n:integer;
begin
    readln(n);
    for i:=1 to n do
    begin
        readln(a[i]);
        readln(b[i]);
    end;

          writeln('Slytherin:');
  for i:=1 to n do
    if b[i]='Slytherin' then
      writeln(a[i]);
      writeln;

  writeln('Hufflepuff:');
  for i:=1 to n do
   if b[i]='Hufflepuff' then
     writeln(a[i]);
     writeln;

  writeln('Gryffindor:');
  for i:=1 to n do
    if b[i]='Gryffindor' then
      writeln(a[i]);
      writeln;
  writeln('Ravenclaw:');
  for i:=1 to n do
    if b[i]='Ravenclaw' then
      writeln(a[i]);

end.