function slide(n, k){
             clearInterval(timer);
             $('#slider'+k).animate({
                opacity: 0

              }, 1000, function() {
                  
              })

              //$('#slider'+k).hide().css('display', 'none');

              $('#slider'+n).css('opacity', 0).show().css('display', 'block').animate({
                opacity: 1
              }, 1000, function() {

              });
              cslider = n;
              
              timer = window.setInterval(function()
                {
                    if (cslider<4&&cslider>=1){
                        if (cslider==4){
                            slide(1, cslider);
                        }else slide(cslider+1, cslider);
                    }else{
                        slide(1, 4);
                        cslider = 1;
                    }
                }, 15000);
        }

var cslider = 1;
var timer = window.setInterval(function()
{
    if (cslider<4&&cslider>=1){
        if (cslider==4){
            slide(1, cslider);
        }else slide(cslider+1, cslider);
    }else{
        slide(1, 4);
        cslider = 1;
    }
}, 15000);