$(document).ready(function(){
  $('.slide__thumbnails .thumb').click(function(){

    var imgThumb = $(this).attr('src');
    var oldImg = $('.full_img');
    var imgFull = $('<img class="full_img" src="' + imgThumb +'">');
    imgFull.hide();
    $('.full').prepend(imgFull);
    imgFull.show(1);
    oldImg.hide(1,function(){
      $(this).remove();
    });
  });
});
$('thumb:first').click();