How to add OptiMonk code to each page before closing body tag?

[5minimum]

To install OptiMonk, I have to add this code to every page just before the closing </body> tag. need to include the code once per page. don't know where to add ?

<script type="text/javascript">
    (function(e,a){
        var t,r=e.getElementsByTagName("head")[0],c=e.location.protocol;
        t=e.createElement("script");t.type="text/javascript";
        t.charset="utf-8";t.async=!0;t.defer=!0;
        t.src=c+"//front.optimonk.com/public/"+a+"/js/preload.js";r.appendChild(t);
    })(document,"134202");
</script>