Tính tổng ma trận sử dụng chương trình con

program tinhtong_matran;
uses crt;
type
  mang=array[1..10,1..10] of integer;
var
  a,b,p:mang;
  i,j,h,c,ha,ca,hb,cb:integer;
procedure nhap(var m:mang; ch:char; var h,c:integer);
begin
  writeln('Nhap ma tran ',ch);
  write('Nhap hang: ');
  readln(h);
  write('Nhap cot : ');
  readln(c);
  for i:=1 to h do
    for j:=1 to c do
      begin
        write(ch,'[',i,',',j,']=');
        readln(m[i,j]);
      end;
end;
procedure xuat(var m:mang; ch:char; var h,c:integer);
begin
  writeln('In ma tran ' , ch);
  for i:=1 to h do
    begin
      for j:=1 to c do write (m[i,j]:3);
      writeln;
    end;
end;
procedure tinhtong(var m,n,t:mang; h,c:integer);
begin
  for i:=1 to h do
    for j:=1 to c do
      t[i,j]:= m[i,j]+n[i,j];
end;
begin
  clrscr;
  nhap(a,'a',ha,ca);
  nhap(b,'b',hb,cb);
  xuat(a,'a',ha,ca);
  xuat(b,'b',hb,cb);
  if (ha=hb) and (ca=cb) then
    begin
      tinhtong(a,b,p,ha,ca);
      xuat(p,'p',ha,ca);
    end
  else
    writeln('Khong tinh tong duoc a,b');
  readln;
end.