program ucln;

uses crt;

var a,b,c : integer;

begin

clrscr;

write('nhap vao 2 so a,b'); readln(a,b);

while a> 0 do

begin

if b>a then

begin

c:=a;

a:=b;

b:=c;

end;

a:=a-b;

end;

writeln('uoc chung lon nhat la ',b);

readln;

end.