I made my array 10000, but still WA.

type
  arr=array [1..10000] of byte;
var
    p1,p2,p3,p4:arr;
    i,j,k,n,pos1,pos2,pos3,pos4:integer;
procedure init;
  begin
  read(n,k);
  p2[1]:=1;
  p3[1]:=k-1;
  pos2:=1;
  pos3:=1;
  end;
procedure plus(p1,p2:arr);
  var i:integer;
  begin
   fillchar(p4,sizeof(p4),0);
   for i:=1 to pos2 do
     begin
     inc(p4[i],p1[i]+p2[i]);
     if p4[i]>=10
       then begin
            inc(p4[i+1],p4[i] div 10);
            p4[i]:=p4[i] mod 10;
            end;
     end;
   if pos1=pos2
     then begin
          if p4[pos2+1]>0 then pos4:=pos2+1
                          else pos4:=pos2;
          end
     else pos4:=pos2;
  end;
procedure multiply(m:integer;p4:arr);
  var i:integer;
      judge:boolean;
  begin
   fillchar(p3,sizeof(p3),0);
   for i:=1 to pos4 do
    begin
    inc(p3[i],m*p4[i]);
    if p3[i]>=10
      then begin
            inc(p3[i+1],p3[i] div 10);
            p3[i]:=p3[i] mod 10;
           end;
    end;
   inc(i); judge:=true;
   while p3[i]>=10 do
     begin
     inc(p3[i+1],p3[i] div 10);
     p3[i]:=p3[i] mod 10;
     inc(i); judge:=false;
     end;
   if (judge)and(p3[i]=0) then pos3:=i-1
   else pos3:=i;
  end;
begin
  init;
  for i:=2 to n do
    begin
    p1:=p2; p2:=p3;
    pos1:=pos2; pos2:=pos3;
    plus(p1,p2);
    multiply(k-1,p4);
    end;
  for i:=pos3 downto 1 do
   write(p3[i]);
  writeln;
end.