let ask i =
  print_int i;
  print_newline();
  let s = read_line() in
  s
in

let rec search : int -> string -> int -> string -> unit = fun l ls r rs ->
  let m = (l+r)/2 in
  let ms = ask m in
  if ms <> "Vacant" then
    if (m-l+1) mod 2 = 0 then
      if ms = ls then
        search l ls m ms
      else
        search m ms r rs
    else
      if ms = ls then
        search m ms r rs
      else
        search l ls m ms
  else
    ()
in


let n = read_int() in
let ls = ask 0 in
if ls <> "Vacant" then
  let rs = ask (n-1) in
  if rs <> "Vacant" then
    search 0 ls (n-1) rs
  else ()
else ()
;;  
   
