Sử dụng hàm viết 3 chương trình con tính tổng,hiệu,tích của 2 số nguyên m,n

uses crt;
var m,n: integer;
{-------------------------------------}
Function Tong(a,b: integer): string;
 begin
  writeln(a+b);
 end;
{-------------------------------------}
Function Hieu(a,b: integer): string;
 begin
  writeln(a-b);
 end;
{-------------------------------------}
Function Tich(a,b: integer): string;
 begin
  writeln(a*b);
 end;
{-------------------------------------}
BEGIN
clrscr;
 write('Nhap m: '); readln(m);
 write('Nhap n: '); readln(n);
 writeln('m+n=',Tong(m,n));
 writeln('m-n=',Hieu(m,n));
 writeln('m*n=',Tich(m,n));
 readln;
END.

uses crt;
var m,n: integer;
function Tong(a,b: integer): string;
begin write(a+b); end;

function Hieu(a,b: integer): string;
begin write(a-b); end;

function Tich(a,b: integer): string;
begin write(a*b); end;

begin
   clrscr;
   write('Nhap m: '); readln(m);
   write('Nhap n: '); readln(n);
   write('m+n=',Tong(m,n));
   writeln;
   write('m-n=',Hieu(m,n));
   writeln;
   write('m*n=',Tich(m,n));
   writeln;
   readln
end.