N, X = gets.split.map(&:to_i)
NS = gets.split.map(&:to_i)

def print_ans(idxs)
  puts (0...N).map{|i| idxs.include?(i) ? "o" : "x"}.join
  exit #こんなところでexitは使いたくない
end

nis = NS.map.with_index{|n,idx| [n,idx]}.select{|a| a[0] <= X}.sort

hash1 = Hash.new
hash1[0] = []
while ni = nis.shift do
  num, idx = ni
  add = {}
  hash1.each do |sum, idxs|
    new_sum = sum + num
    print_ans(idxs.dup << idx) if new_sum == X
    add[new_sum] = idxs.dup << idx if new_sum < X && !hash1[new_sum]
  end  
  hash1.update(add)
  break if hash1.size >= 100_000
end

hash2 = Hash.new
hash2[0] = []
while ni = nis.shift do
  num, idx = ni
  add = {}
  hash2.each do |sum, idxs2|
    new_sum = sum + num
    idxs1 = hash1[X - new_sum]
    print_ans((idxs1 + idxs2) << idx) if idxs1
    add[new_sum] = idxs2.dup << idx if new_sum < X && !hash2[new_sum]
  end
  hash2.update(add)
end

puts "No"