In ASP .NET how to used three repeater inside with each other..?

to get the repeater ( Rp2 ) it is inside (Rp1) to access the Rp2 items by :

for(int i=0;i<rp1.items.count;i++)>
{
Repeater Rp2= ((Repeater)Rp1.Items[i].FindControl("Rp2"));

//then loop Rp2

for(int j=0;j<rp2.items.count;j++)>
{
TextBox txtname = ((TextBox)Rp2.Items[j].FindControl("txtname")); // textbox inside repeater2
}

}