input = gets.chomp                                                                                                                                              
input += 'o' * 15                                                                                                                                               
victories = input[0..14]                                                                                                                                        
if 8 <= victories.split(//).select{|v| v == 'o'}.count                                                                                                          
  puts 'YES'                                                                                                                                                    
else                                                                                                                                                            
  puts 'NO'                                                                                                                                                     
end     