var SCROLL_PHOTO = 4;
 var ONE_FRAME = 100;
 var SCROLL_STEP = 5;
 var PADDING = 30;

 var _dom = document.all?(document.getElementById?2:1):(document.getElementById?4:(document.layers?3:0));

 function start()
  {
   var ss = getScreenSize();
   var h = ss.y - (PADDING * 2);

   var cont_l = document.getElementById('cont_lId');
   cont_l.style.top = PADDING + 'px';
   cont_l.style.height = h + 'px';
   cont_l.style.display = '';
   document.getElementById('cont_lImgId').style.height = (h - 40) + 'px';

   var cont_r = document.getElementById('cont_rId');
   cont_r.style.top = PADDING + 'px';
   cont_r.style.height = h + 'px';
   cont_r.style.display = '';
   document.getElementById('cont_rImgId').style.height = (h - 40) + 'px';

   window.onscroll = function()
    {
     if(!f_scroll) scroll();
    }

   onscroll();
  }

 var f_btn_l = false;
 function up_l()
  {
   obj = document.getElementById('cont_lImgId');
   if(obj.scrollTop != (obj.scrollHeight - obj.offsetHeight))
    {
     if(obj.scrollTop + SCROLL_PHOTO <= (obj.scrollHeight - obj.offsetHeight))
       obj.scrollTop = obj.scrollTop + SCROLL_PHOTO;
     else
      {
       obj.scrollTop = (obj.scrollHeight - obj.offsetHeight);
       f_btn_l = false;
      }
    }
   if(f_btn_l == 'up')
     setTimeout(up_l, 1);
  }
 function down_l()
  {
   obj = document.getElementById('cont_lImgId');
   if(obj.scrollTop != 0)
    {
     if(obj.scrollTop - SCROLL_PHOTO > 0)
       obj.scrollTop = obj.scrollTop - SCROLL_PHOTO;
     else
      {
       obj.scrollTop = 0;
       f_btn_l = false;
      }
    }
   if(f_btn_l == 'down')
     setTimeout(down_l, 1);
  }

 var f_btn_r = false;
 function up_r()
  {
   obj = document.getElementById('cont_rImgId');
   if(obj.scrollTop != (obj.scrollHeight - obj.offsetHeight))
    {
     if(obj.scrollTop + SCROLL_PHOTO <= (obj.scrollHeight - obj.offsetHeight))
       obj.scrollTop = obj.scrollTop + SCROLL_PHOTO;
     else
      {
       obj.scrollTop = (obj.scrollHeight - obj.offsetHeight);
       f_btn_r = false;
      }
    }
   if(f_btn_r == 'up')
     setTimeout(up_r, 1);
  }
 function down_r()
  {
   obj = document.getElementById('cont_rImgId');
   if(obj.scrollTop != 0)
    {
     if(obj.scrollTop - SCROLL_PHOTO > 0)
       obj.scrollTop = obj.scrollTop - SCROLL_PHOTO;
     else
      {
       obj.scrollTop = 0;
       f_btn_r = false;
      }
    }
   if(f_btn_r == 'down')
     setTimeout(down_r, 1);
  }

 var f_scroll = false;
 function scroll()
  {
   obj = document.getElementById('cont_lId');
   obj_r = document.getElementById('cont_rId');

   if(parseInt(obj.style.top) != (PADDING + document.body.scrollTop))
    {
     if(parseInt(obj.style.top) > PADDING + document.body.scrollTop)
       if(parseInt(obj.style.top) - SCROLL_STEP < PADDING + document.body.scrollTop)
        {
         obj.style.top = PADDING + document.body.scrollTop;
         obj_r.style.top = PADDING + document.body.scrollTop;
        }
       else
        {
         obj.style.top = parseInt(obj.style.top) - SCROLL_STEP;
         obj_r.style.top = parseInt(obj.style.top) - SCROLL_STEP;
        }
     else if(parseInt(obj.style.top) < PADDING + document.body.scrollTop)
       if(parseInt(obj.style.top) + SCROLL_STEP > PADDING + document.body.scrollTop)
        {
         obj.style.top = PADDING + document.body.scrollTop;
         obj_r.style.top = PADDING + document.body.scrollTop;
        }
       else
        {
         obj.style.top = parseInt(obj.style.top) + SCROLL_STEP;
         obj_r.style.top = parseInt(obj.style.top) + SCROLL_STEP;
        }
     setTimeout(scroll, 1);
     f_scroll = true;
    }
   else
     f_scroll = false;
  }

function getScreenSize()
 {
  var width = 0, height = 0;
  if(typeof(window.innerWidth) == 'number') {
    //Non-IE
    width = window.innerWidth - 4;
    height = window.innerHeight - 4;
  } else if(document.documentElement && (document.documentElement.clientWidth || document.documentElement.clientHeight)) {
    //IE 6+ in 'standards compliant mode'
    width = document.documentElement.clientWidth;
    height = document.documentElement.clientHeight;
  } else if(document.body && (document.body.clientWidth || document.body.clientHeight)) {
    //IE 4 compatible
    width = document.body.clientWidth;
    height = document.body.clientHeight;
  }
  return {
   x : width,
   y : height
  };
 }