var
	fi, fo : text;
  n, m, k, i, s, d, suma : longint;
  mica : boolean;
begin
	assign(fi,'stergeri.in'); reset(fi);
  assign(fo,'stergeri.out'); rewrite(fo);
  readln(fi, n, m, k);
  mica := true;
  for i := 1 to m do
  	begin
    	readln(fi, s, d);
      if s <= k then
      	mica := false;
      inc(suma,d-s+1);
    end;
  if mica then
    writeln(fo, k)
  else
  	writeln(fo, suma+k);
  close(fi); close(fo);
end.

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1567890

3+20+3=26