allPossibleSolutions = []
def helper(arr, spotsTaken, ind):
      if ind == len(arr):
        return
      for j in range(arr[ind][0], arr[ind][1]+1):
        if j not in spotsTaken:
            allPossibleSolutions.append(spotsTaken+[j])
            helper(arr, spotsTaken+[j], ind+1)
            
def max_meetings(times): 
    helper(times, [], 0)
    myMax = 0
    for sol in allPossibleSolutions:
        if len(sol) > myMax:
            myMax = len(sol)
    return myMax
    
ret = max_meetings([[2, 2], [4, 5], [4, 10], [5, 6], [5, 7], [6, 6]])