position=0;


function image_next() {
    if (position != parseInt(max) - 5) {
        position++;
        anchor = document.getElementById("galer" + position);
        anchor.style.display = "none";
        position2 = position + 3;
        anchor = document.getElementById("galer" + position2);
        anchor.style.display = "block";
        image = document.getElementById("main_image");
        image.src=url+position+'.jpg';
    }
    
}

function image_prev() {
    if (position != 0) {
        position2 = position + 3;
        anchor = document.getElementById("galer" + position2);
        anchor.style.display = "none";
        anchor = document.getElementById("galer" + position);
        anchor.style.display = "block";
        image = document.getElementById("main_image");
        image.src=url+position+'.jpg';
        position--;
    }
}