static void Main(string[] args)
    {            try            {
            Microsoft.SharePoint.Client.ClientContext clientContextproj =
        new Microsoft.SharePoint.Client.ClientContext("");
            Web siteproj = clientContextproj.Web;
            // clientContextproj.AuthenticationMode =
             //ClientAuthenticationMode.Default;
            // clientContextproj.Credentials = new
         //System.Net.NetworkCredential("username", "password",
              //"domain");
            CamlQuery query1 = new CamlQuery();
            query1.ViewXml = "<View><Query><FieldRef Name='Country'/>
             <Value Type='Text'></Value></Query></View>";

            List resourceMaster = siteproj.Lists.GetByTitle("Test1");
            Microsoft.SharePoint.Client.ListItemCollection items =
           resourceMaster.GetItems(query1);
            clientContextproj.Load(items);
            clientContextproj.ExecuteQuery();
            Excel.Application ap = new Excel.Application();
            Excel.Workbook wb =
          ap.Workbooks.Open("C:\Users\sa06\Desktop\Report.xlsx");
            Excel.Worksheet ws = wb.ActiveSheet;
            bool flag = true;
            int counter = 2;
            while (flag)
            {
                string columnHeader = "A" + counter.ToString();
                Microsoft.Office.Interop.Excel.Range row =
               ws.get_Range(columnHeader);
                row.Value2 = row.Text.ToString().Trim();
                if (row.Value2 != null)
                {
                    if (items.Count != 0)
                    {
                        foreach (ListItem listItem in items)
                        {
                            Console.WriteLine(listItem["Country"]);
                            var currentResourceId = listItem["Country"];
                    if (currentResourceId != null &&
                   currentResourceId.Equals(row.Value2))
                            {
                   Microsoft.Office.Interop.Excel.Range Exprow =
                   ws.get_Range("B" + counter.ToString());
                                    string ValueTotal =
                     Convert.ToString(Exprow.Value2);
                                    listItem["Region"] = ValueTotal;
                                    listItem.Update();
                                    clientContextproj.ExecuteQuery();
                                    break;
                            }                              }
                        }                        }
                    else
                    {                            flag = false;       }
                }                 }

          catch (Exception ex)
          {
            throw ex;
          }
      }