Найти произведение двумерных массивов

uses crt;
const n=5;
type mas=array[1..n,1..n] of integer;
procedure matrix(var a:mas;s:char);
var i,j:byte;
begin
writeln('Њ*ваЁж* ',s);
for i:=1 to n do
 begin
  for j:=1 to n do
   begin
    a[i,j]:=random(10);
    write(a[i,j]:4);
   end;
  writeln;
 end;
end;
 
procedure umn(a,b:mas;var c:mas;s:string);
var i,j,k:byte;
begin
for i:=1 to n do
for j:=1 to n do
 begin
  c[i,j]:=0;
  for k:=1 to n do
  c[i,j]:=c[i,j]+a[i,k]*b[k,j];
 end;
writeln(s);
for i:=1 to n do
 begin
  for j:=1 to n do
  write(c[i,j]:4);
  writeln;
 end;
end;
function max(a:mas):integer;
var i,j:byte;
    mx:integer;
begin
mx:=a[1,1];
for i:=1 to n do
for j:=1 to n do
if a[i,j]>mx then mx:=a[i,j];
max:=mx
end;
var a,b,c,ab,bc,ac:mas;
begin
clrscr;
randomize;
matrix(a,'A');
matrix(b,'B');
matrix(c,'C');
write('Press Enter');
readln;
umn(a,b,ab,'Matrix A*B');
writeln('Max=',max(ab));
umn(b,c,bc,'Matrix B*C');
writeln('Max=',max(bc));
umn(a,c,ac,'Matrix A*C');
writeln('Max=',max(ac));
readln
end.