let () =
  let a = Array.make 3 false in
  let n = Scanf.scanf "%d " (fun i -> i) in
  a.(n-1) <- true;
  let m = Scanf.scanf "%d " (fun i -> i) in
  for i = 0 to m - 1 do
    let p, q = Scanf.scanf "%d %d " (fun p q -> p, q) in
    let p, q = p - 1, q - 1 in
    let t = a.(p) in
    a.(p) <- a.(q);
    a.(q) <- t
  done;
  let rec doit i =
    if a.(i) then i + 1
    else doit (i + 1) in
  doit 0 |> Printf.printf "%d\n"