copying the one gridview value to another gridview using dataset

ArrayList da1 = new ArrayList();
            ArrayList da2 = new ArrayList();
            int a1 = 0;
            int  a2 = 0;
           
         
         DataSet dc = (DataSet) Session["dtb"];
        //DataRow tr = (DataRow)Session["dg"];

        foreach (GridViewRow row1 in grv1.Rows)
        {
            a1 = int.Parse(row1.Cells[3].Text);
           
            da1.Add(a1);
                
        }
        int ri = 0;
        //int rd = 0;
        foreach (GridViewRow row1 in grv1.Rows)
        {
            
            //foreach (GridViewRow row2 in grv2.Rows)
            //{
            foreach (DataRow dr in dc.Tables[0].Rows)
            {
               //rd = int.Parse(dr.ToString());
                foreach (int ir in da1)
                {
                    
                  
                    for (; ri < ir; ri++)
                    {

                        //row2.Cells[1].Text = row1.Cells[1].Text;
                       dr[1] = row1.Cells[1].Text;
                     
                        

                    }

                    ri = ir;

                }

                //break; 
            }
            //break;

            //    continue;
        }

grv2.DataSource= dc;
                                
                 
        }