A natural number, if read from left to right and reversed from right to left, is the same, then this number is called "palindromic number", such as 8, 66, 141, 5225 are all palindromic numbers, and 332 It is not a palindrome number, so what is the 1999th palindrome number from small to large.
一个自然数，如果从左往右顺读和从右往左逆读，都是一样的，则这个数称为"回文数"，如8，66，141，5225都是回文数，而332不是回文数，那么从小到大的第1999个回文数是多少．
<result>999_999</result>