a = gets.chomp.split('')
rem = 15 - a.length
l, w = 0, 0
a.each do |m|
  if m == 'o'
    w += 1
  else
    l += 1
  end
end
if w >= 8 || rem >= 8
  puts 'YES'
elsif rem <= 8 && 8 - w <= rem
  puts 'YES'
else
  puts 'NO'
end