program NSD;

uses Crt;

var A, B : integer;

begin

  write('Zadej 1. cislo: '); read(A);

  write('Zadej 2. cislo: '); read(B);

  while A<>B do

                        if A>B then A:=A-B

                               else B:=B-A;

  writeln('NSD = ',A);

  repeat until keypressed;

end.