Lecture 3 - slide 19 : 39

program gcdprog;
uses crt;
  var i,j: integer;

  function gcd(Input1, Input2: Integer): Integer;
  var Stor, Lille, Rest: Integer;
  begin
    Stor := Input1;  Lille := Input2;
    while Lille > 0
    do begin
         Rest := Stor mod Lille
         Stor := Lille;
         Lille := Rest
       end; 
    gcd := Stor
  end;

begin
  clrscr;
  writeln('Indtast to positive heltal, det stoerte foerst');
  readln(i,j);
  writeln('GCD = ', gcd(i,j));
  readkey
end.