Two matrix multiplication program

uses wincrt;
var
a,b,c : array [1..3,1..3] of integer;
i,j,k : integer;

begin
 writeln ('masukan nilai matriks a:');
 for i:=1 to 3 do
  for j:=1 to 3 do
 begin
  write ('data ke_',i,',',j,':');
  readln ( a [i][j]);
 end;

 writeln ('==============');
 writeln ('masukan nilai matriks b:');
 for i:=1 to 3 do
  for j:=1 to 3 do
  begin
  write ('data ke-',i,',',j,':');
  readln (b [i][j]);
  end;

 writeln ('==============');
 writeln (' hasil perkalian matriks a dengan matriks b :');
 for i:= 1 to 3 do
  begin
  for j := 1 to 3 do
  begin
  for k := 1 to 3 do
  c [i,j]:=c[i,j]+a[i,k]*b[k,j];
  write (c [i] [j]:4);
  end;
  writeln;
  end;

end.