var activeItemIndex = 0;
function hidden() {
    document.getElementById('ph1').style.display = 'none';
    document.getElementById('ph2').style.display = 'none';
    document.getElementById('ph3').style.display = 'none';
    document.getElementById('ph4').style.display = 'none';
}
function view_pic(div) {
    var v = document.getElementById('ph' + div);
    if (v) {
        hidden();
        v.style.display = 'block';
        activeItemIndex = div;
    } return false;
}
function chang_pic() {
    if (activeItemIndex >= 4) { activeItemIndex = 0; };
    activeItemIndex++;
    setTimeout("chang_pic()", 5000);
    view_pic(activeItemIndex);
}