var prev_img = 0;

$(document).ready(function(){ 

        $("#prev_"+prev_img).show();
        setTimeout(rotate_prev,5000);

});

function rotate_prev() {
    var total_images = $(".prev_img").length - 1;

    $("#prev_"+prev_img).fadeOut(function() {
        prev_img = prev_img + 1;
        if(prev_img > total_images) {
            prev_img = 0;
        }
        $("#prev_"+prev_img).fadeIn(function() {
            setTimeout(rotate_prev,5000);
            
        });
        
        
        });

    
}