在纸上写着一排数字，每个数字都介于1-N之间，数字按升序排列，中间没有空格，然后其中一些数字的某些字符被擦掉了。上剩下的字符按序存放在一个字符串leftDigits中。给定字符串leftDigits，其中每个字符是( 0 - 9 ) 中的一个。问：N 最小可能是多少？请编程实现-To write a row of figures, between each number between 1-N, numbers in ascending order, no intervening spaces, then some characters, some of which were erased digital. The rest of the characters are stored in a string in leftDigits sequence. Given a string leftDigits, where each character is one of the ( 0 - 9 ). Question: N what is the smallest possible? Please programming