{# Grading needs an account, so show the task but not a runner
that would fail the moment it is submitted. #}
Kirish
Sonlar qatori: 2, 6, 12, 20, ?
Qiyin
Sonlar orasidagi farqqa e'tibor bering.
Mashqni yechish uchun hisobingizga kiring
Javobingiz tekshiriladi, izoh beriladi va XP yig'iladi.