You are given two lists of availability time intervals, slots1 and slots2, where each interval is represented as [start, end]. You are also given an integer duration representing the required length of a meeting.

Return the earliest time interval [meetingStart, meetingEnd] such that:
the meeting fits entirely within an interval from slots1 and within an interval from slots2, and meetingEnd - meetingStart = duration.

If no such time interval exists, return an empty list.

Constraints:

• $1 \leq$ slots1.length, slots2.length $\leq 10^4$

• slots1[i].length $=$ $2$ and slots2[i].length $=$ $2$

• slots1[i][0] $<$ slots1[i][1]

• slots2[i][0] $<$ slots2[i][1]

• $0 \leq$ slots1[i][j], slots2[i][j] $\leq 10^9$

• $1 \leq$ duration $\leq 10^6$

Input: slots1 = [[5,25],[30,55],[80,120]]-List[List[int]], slots2 = [[0,10],[20,35],[50,90]]-List[List[int]], duration = 10-int
Output: [80,90]-List[int]
Explanation: The earliest overlap of length at least 10 occurs between [80,120] and [50,90], giving the intersection [80,90], which fits exactly 10 minutes.

Input: slots1 = [[0,5],[10,15]]-List[List[int]], slots2 = [[6,9],[16,20]]-List[List[int]], duration = 3-int
Output: []-List[int]
Explanation: None of the intervals overlap, so there is no common window long enough to schedule a 3-minute meeting.

Input: slots1 = [[100,200]]-List[List[int]], slots2 = [[150,160],[170,300]]-List[List[int]], duration = 20-int
Output: [170,190]-List[int]
Explanation: The overlap with [150,160] is only 10 minutes (too short), while the overlap with [170,300] is [170,200], which is 30 minutes, so the earliest valid 20-minute meeting is [170,190].

Input: slots1 = [[0,1000000000]]-List[List[int]], slots2 = [[999999000,1000000000]]-List[List[int]], duration = 1000-int
Output: [999999000,1000000000]-List[int]
Explanation: The intersection is [999999000,1000000000], which is exactly 1000 minutes long, so it is a valid meeting window and also the earliest possible.

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