N, M = gets.split.map(&:to_i)
S = gets.chomp

a_pos = []
w_pos = []

S.each_char.with_index do |s, i|
  case s
  when 'W'
    w_pos << i
  when 'A'
    a_pos << i
  else
    if a_pos.empty?
      puts 'No'
      exit
    else
      a_pos.shift
    end
  end
end

until w_pos.empty?
  l = w_pos.shift

  if a_pos.last < l
    puts 'No'
    exit
  end
end

puts 'Yes'