Can I get rid of C libraries dependencies?

[Leff Ivanov <droiddermo@gmail.com>]

Okey, so I wrote this code:

pragma No_Run_Time;

with Interfaces.C.Strings;
use  Interfaces.C.Strings;
with Interfaces.C;
use  Interfaces.C;

procedure Main is
   procedure cputs(str:Char_Array);
   pragma Import(C, cputs, "puts");
   
   procedure cexit(code:Integer);
   pragma Import(C, cexit, "exit");
begin
   cputs("Hello World!");
   cexit(0);
end Main;

What I want to achive is a tiny 2kb binary executable 
with a single function called as entry point (which is 
defined in Ada and called Main procedure). The pragma 
on top let me get rid of the huge RTL code that is written
in Ada. However I'm still getting a lot of code linked 
in from C libraries, so...

1) Can I get rid of the C code linked in?
2) What is implemented in thoose C libraries?
3) Can I use Ada's RTL library without the C 
   support code, if I use some Restrictions?