ImageButton Onclick Property

Question

In my web form i have 5 imageButtons. Each Imagebutton call the same method on "OnClick" property. like:

<asp:ImageButton ID="ImageButton1" ImageUrl="~/Category_Icon/Computer2.jpg" runat="server"  OnClick="call" ></asp:ImageButton>

<asp:ImageButton ID="ImageButton2" ImageUrl="~/Category_Icon/Computer2.jpg" runat="server"  OnClick="call" ></asp:ImageButton>

<asp:ImageButton ID="ImageButton3" ImageUrl="~/Category_Icon/Computer2.jpg" runat="server"  OnClick="call" ></asp:ImageButton>

<asp:ImageButton ID="ImageButton4" ImageUrl="~/Category_Icon/Computer2.jpg" runat="server"  OnClick="call" ></asp:ImageButton>

<asp:ImageButton ID="ImageButton5" ImageUrl="~/Category_Icon/Computer2.jpg" runat="server"  OnClick="call" ></asp:ImageButton>



Now my question is that how can i find that which ImageButton's Onclick event occure.
means i want to find the name of imagebutton which call the method.