function pagScroll(id, offset) {
    var container = document.getElementById(id);
    var oldscroll = container.scrollTop;

    container.scrollTop += offset;
    
    if(oldscroll != container.scrollTop) {
        if(offset < 0)
            document.getElementById('pag_current').innerHTML = parseInt(document.getElementById('pag_current').innerHTML) - 1;
        else
            document.getElementById('pag_current').innerHTML = parseInt(document.getElementById('pag_current').innerHTML) + 1;
    }
    
}

function setNumPages() {
    var num_pages = Math.ceil(container.scrollHeight/con_parent.offsetHeight);
    
    if(num_pages > 1) {
        document.getElementById("pag_total").innerHTML = num_pages;
        document.getElementById("nav").style.display   = "block";
    }
}