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 :=  false;
  for i := 1 to m do
  	begin
    	readln(fi, s, d);
      if s < k then
      	mica := true;
      inc(suma,d-s+1);
    end;
  if mica then
  	writeln(fo, suma+k)
  else
  	writeln(fo, k);
  close(fi); close(fo);
end.

123456789012345678901234567890
1567890

3+20+3=26