2-6-class-1.dart

main() {
  var userMain = User();
  userMain.name = 'Boris';
  print('Your name: ${userMain.name}');
  
  var st = Student(2020);
  st.name = 'Stas';
  st.surname = 'Konovalov';
  print('New student: $st');
}

class User {
  String name;
  String surname;
  int sex; 
}

class Student extends User {
  int yearOfAdmission;
  int get cuttentCourse => (DateTime.now().year - yearOfAdmission + 1);
  
  Student(this.yearOfAdmission);
    
  @override
  String toString() {
    return '$name $surname $yearOfAdmission $cuttentCourse';
  }
}