Почему в случае 1 10 ответ 9 если 0 тоже число в котором не идут два подряд ноля?

Просто 2 раза получил ВА, поменял на 9 и АС.

N ≥ 2. Test "1 10" is incorrect; there is no such test in the test set.

You are wrong. In case 1 10 you have exactly nine 1-digit numbers without two or more subsequent zeros. They are: 1,2,3,4,5,6,7,8 and 9.

What do you mean? '0' is *also* a 1-digit number without two or more subsequent zeroes, no?

Also, yay for necroposting!