A positive integer is lucky if each digit in its base-ten representation, starting from the leftmost digit, is not more than the digit on its right. For example, 79, 335 and 679 are lucky numbers but 41, 523 and 786 are not. A super-lucky number is a lucky number with 8 in its ones place and whose square is also lucky. Find the smallest super-lucky number. có lời giải bằng tiếng anh đầy đủ ạ