# Time:  O(n)
# Space: O(n)

class Solution(object):
    def kEmptySlots(self, flowers, k):
        """
        :type flowers: List[int]
        :type k: int
        :rtype: int
        """
        days = [0] * len(flowers)
        for i in xrange(len(flowers)):
            days[flowers[i]-1] = i
        result = float("inf")
        i, left, right = 0, 0, k+1
        while right < len(days):
            if days[i] < days[left] or days[i] <= days[right]:
                if i == right:
                    result = min(result, max(days[left], days[right]))
                left, right = i, k+1+i
            i += 1
        return -1 if result == float("inf") else result+1