# https://leetcode.com/problems/k-th-smallest-in-lexicographical-order

class Solution:
    def findKthNumber(self, n: int, k: int) -> int:
        def max_step(curr: int) -> int:
            step = 0
            first, last = curr, curr
            while first <= n:
                step += min(n, last) - first + 1
                first *= 10
                last = last * 10 + 9
            return step
        curr = 1
        k -= 1
        while k > 0:
            step = max_step(curr)
            if step <= k:
                k -= step
                curr += 1
            else:
                k -= 1
                curr *= 10
        return curr