# まだTLEのはず

N, X = gets.split.map(&:to_i)
H = Hash.new{|h,k| h[k] = []}
T = gets.split.map(&:to_i)
T.each_with_index{|n,i| H[n] << i}
A = H.to_a.sort.reverse
S = T.inject(&:+)

def check(a, i, x, s)
  throw :ok, a if x == 0
  return if x < 0
  return if s < x
  return if i >= A.size

  num, idxs = A[i]
  idxs.size.downto(0) do |m|
    check(a.dup.concat(idxs[0...m]), i + 1, x - num * m, s - num * idxs.size)
  end
end

ans = catch(:ok) do
  check([], 0, X, S)
  []
end

puts ans.size > 0 ? (0...N).map{|i| ans.include?(i) ? "o" : "x"}.join : "No"