PL/SQL - Accept two numbers and print the largest number

declare

       x number;
       y number;
begin
      x :=&x;
      y :=&y;
      if( x > y)then
       dbms_output.put_line('x is largest than y');
       else
          dbms_output.put_line('y is largest than x');
   
      end if;
end;