< %@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script src="./js/jquery-1.11.3.js"></script>
<script src="http://code.jquery.com/jquery-1.11.3.min.js"></script>
<title>Insert title here</title>
<script type="text/javascript">
function plus(){
    num = Number(num) + 1;
    document.getElementById("txt").value = num;
    main()
}
var str = "";
var num = "0";
function main(){
    str = "";
    str+= '<input type="button" id="b1" value="+1">';
    str+= '<input type="text" id="txt" value="'+ num +'">';
    str+= '<input type="button" id="b2" value="-1">';
   
    document.getElementById("main")[removed] = str;
}
function minus(){
    num = Number(num) - 1;
    document.getElementById("txt").value = num;
    main()
}
window.>     main();
    var btn1 = document.getElementById("b1");
    btn1.>     var btn2 = document.getElementById("b2");
    btn2.>}
</script>
</head>
<body>
    <div id="main"></div>
</body>
</html>


위에 b1이랑 b2를 눌리면 txt에 +1 , -1해서 값을 갱신할려고하는데요


처음에 1번만 제대로 실행되고 그다음부터는 먹통이에요 이거 왜그런가요 ㅠ?