SQL & PL/SQL

hi,
I've been trying to insert multiple rows in a table from user input by some pl/sql, but failed every time. :/
what happens is that the program suppose to ask the user every time for new value but the loop
actually inserts the 1st values four times ( the loop is ran four times ). can any one point out what i'm
doing wrong or some solutions will be nice ;)

here what i wrote

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set serveroutput on
set verify off

declare

empno number;
empname varchar2(20);

begin

for i in 1..4 loop
empno:=&empno;
empname:='&empname';

insert into employee values(empno,empname);

end loop;

end;

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dont laugh at my code, i'm new to this oracle :D

thanks, looking forward for some reply