using System;

class Solution
{
    public static int[] MeetingPlanner(int[,] slotsA, int[,] slotsB, int dur)
    {
      if(slotsA == null || slotsB == null || dur <= 0)
      {
        return new int[0];
      }

      var rowsA = slotsA.GetLength(0);
      var rowsB = slotsB.GetLength(0);

      int indexA = 0;
      int indexB = 0;

      while(indexA < rowsA && indexB < rowsB)
      {
        var startA = slotsA[indexA, 0];
        var endA   = slotsA[indexA, 1];

        var startB = slotsB[indexB, 0];
        var endB   = slotsB[indexB, 1];

        var overlapStart = Math.Max(startA, startB);
        var overlapEnd   = Math.Min(endA, endB);

        var interval = overlapEnd - overlapStart;
        if(interval >= dur)
        {
          return new int[]{overlapStart, overlapStart + dur};
        }
        else if(endA < endB)
        {
          indexA++;
        }
        else
        {
          indexB++;
        }
      }

      return new int[0];
    }

    static void Main(string[] args)
    {

    }
}

/*
keyword:
Each solts, nonoverlap , sorted by start time, ascending order
two intervals overlap -> given dur -> return
advance one of pointers

 10       50   60  120
  -----------   ___________

0    15
_____


___________________
  |______|


  max - min overlap - nonexist


time complexity :

O(n + m), n time solts, m length of time slots second one

*/