Найти произведения массивов. Произведение двух массивов описать как процедуру

uses crt;
const n=5;
type mas=array [1..n, 1..n] of longint;
var
a,b,c,d,f,res,res1:mas;
i,j:integer;
 
procedure mumnog(a,b:mas; var res:mas);
var
k:integer;
 begin
  for i:=1 to 5 do
   for j:=1 to 5 do
      begin
       res[i,j]:=0;
       for k:=1 to 5 do
       res[i,j]:=res[i,j]+a[i,k]*b[k,j];
         end;
           end;
BEGIN
clrscr;
randomize;
for i:=1 to  n do
 for j:=1 to n do
 begin
 a[i,j]:=random(20); a[i,j]:=a[i,j]-10;
 b[i,j]:=random(20); b[i,j]:=b[i,j]-10;
 c[i,j]:=random(20); c[i,j]:=c[i,j]-10;
 d[i,j]:=random(20); d[i,j]:=d[i,j]-10;
 f[i,j]:=random(20); f[i,j]:=f[i,j]-10;
 end;
gotoxy(1, 3);
write('A=');
gotoxy(3,1);
for i:=1 to n do
 begin
 for j:=1 to n do
  write(a[i,j]:6);
 gotoxy(3,wherey+1)
 end;
gotoxy(38,1);
write('B=');
gotoxy(40,1);
for i:=1 to n do
 begin
 for j:=1 to n do
  write(b[i,j]:6);
 gotoxy(40, wherey+1);
 end;
gotoxy(1,9);
write('C=');
gotoxy(3,7);
for i:=1 to n do
 begin
 for j:=1 to n do
  write(c[i,j]:6);
 gotoxy(3, wherey+1);
 end;
gotoxy(38,9);
write('D=');
gotoxy(40,7);
for i:=1 to n do
 begin
 for j:=1 to n do
  write(d[i,j]:6);
 gotoxy(40, wherey+1);
 end;
gotoxy(1,15);
write('F=');
gotoxy(3,13);
for i:=1 to n do
 begin
 for j:=1 to n do
  write(f[i,j]:6);
 gotoxy(3, wherey+1);
 end;
mumnog(a,b, res);
mumnog(res,c,res1);
mumnog(res1,d,res);
mumnog(res,f,res1);
gotoxy(36,15);
write('RES=');
gotoxy(40,13);
for i:=1 to n do
 begin
 for j:=1 to n do
  write(res1[i,j]:6);
 gotoxy(40, wherey+1);
 end;
readkey;
end.