program stergeri;
var f,g:text;
    n,m,k,a,b,i,c1,c2:longint;
begin
assign(f,'stergeri.in');
assign(g,'stergeri.out');
reset(f);
rewrite(g);
read(f,n,m,k);
for i:=1 to m do
  begin
    read(f,a,b);
    if (a<k)and(b<k)then inc(c1,b-a)else
    if (a<=k)and(b>=k)then
      begin
        inc(c1,k-a+1);
        inc(c2,b-k);
      end else inc(c2,b-a+1);
  end;
write(g,k+c1+c2);
close(f);
close(g);
end.