Program Deret Bilangan Berbentuk Cekung

program cekung;
uses wincrt;

var c,a,i,j,f,k,h:integer;

begin
write('masukkan nilai i : ');
read(a);
c:=a mod 2;
f:=a div 2;

if (a mod 2=1) then
   begin;
   for i:=1 to f+1 do
       begin;
        write(i,'  ');      
        for j:=1 to a-i+1 do write (j,' ');
        writeln
       end;
   for k:=a-f+1 to a do
       begin;
        write(k,'  ');
        for h:=1 to k do write (h,' ');
        writeln;
       end;     
   end

else
   begin;
   for i:=1 to f do
       begin;
        write(i,'  ');      
        for j:=1 to a-i+1 do write (j,' ');
        writeln
       end;
   for k:=a-f+1 to a do
       begin;
        write(k,'  ');
        for h:=1 to k do write (h,' ');
        writeln;
       end;     
   end;
end.