关于返回前面的页面

private void page_load(object sender, system.eventargs e)
        {
            
            viewstate["submittimes"]=convert.toint32(viewstate["submittimes"])+1;
                        if(!page.ispostback)
            {
                viewstate["submittimes"]=1;


            }
        }

页面：
<input type="button" value="button" onclick=history.go(-<%= (int)viewstate["submittimes"] %>)>