<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!DOCTYPE html>
<html>
<body>
<input type="text" id="fst">
<input type="text" id="sec">
<input type="text" id="thr">
<button type="button" onclick="fun()">Frst click</button>
<input type="text" id="1">
<input type="text" id="2">
<input type="text" id="3">
<button type="button" onclick="fun2()">Sec Click</button>
<p id="demo"></p>
<p id="demo1"></p>
<script>
function fun(){
var one=document.getElementById('fst').value
var two=document.getElementById('sec').value
var three=document.getElementById('thr').value
document.getElementById('demo'). innerHTML=cal(one,two,three);
}
function fun2(){
