jquery - Slider going too far -

i making slider website , have done except slider goes 1 further need. can tell me why? need left hide after has been clicked twice instead hides after click 3 times.

here link site on http://alanvitek.com/dev

here jquery

jquery(function($){     var sec = $('.portfoliowide'), secwidth = sec.width(), unit = 1040;      $(".button-next").click(function() {         var left = sec.css('left');         left = math.abs(parseint(left.substring(0, left.length - 2)))         if(left + unit >= secwidth){             $(this).hide()         }          sec.animate({left: "-=" + unit }, "slow");         $(".button-back").show();     });