def iter a
  ns = []
  for i in 0 ... 10
    b = a + i.to_s
    b = b + '0' while b.length < 10
    puts b
    STDOUT.flush
    n, res = gets.chomp.split
    ns[i] = n.to_i
    if res == 'unlocked'
      exit(0)
    end
  end

  mx = ns[0]
  idx = 0
  for i in 0 ... 10
    if mx < ns[i]
      mx = ns[i]
      idx = i
    end
  end

  iter (a + idx.to_s)

end

iter ''