text: student_list = ['zarina','emir','bayza', 'nazira']
  current_list = []
  i = 0
  student_len = len(student_list)
  come_in = 1
  while come_in != '0':
      come_in = input('vvedite imya studenta:')
      if come_in not in current_list: #prishedshii
          if come_in in student_list:  # proveryaem
              current_list.append(come_in)  # dobavim studenta
              print('prishel')
          else:
              print('takogo studenta net')
      else:
          print('student uje prishol')
  print(current_list)