uses crt;
var a,b:integer;
begin
clrscr;
repeat
write('Nhap a='); readln(a);
write('Nhap b='); readln(b);
until (a>0) and (b>0);
if a>b then writeln(a,' la so lon hon')
else if a<b then writeln(b,' la so lon hon')
else writeln('Hai so bang nhau');
readln;
end.