description: You are given two integers n and m. Find the \operatorname{MEX} of the sequence n ⊕ 0, n ⊕ 1, …, n ⊕ m. Here, ⊕ is the [bitwise XOR operator](https://en.wikipedia.org/wiki/Bitwise_operation#XOR).
  
  \operatorname{MEX} of the sequence of non-negative integers is the smallest non-negative integer that doesn't appear in this sequence. For example, \operatorname{MEX}(0, 1, 2, 4) = 3, and \operatorname{MEX}(1, 2021) = 0. 
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 30 000) — the number of test cases.
  
  The first and only line of each test case contains two integers n and m (0 ≤ n, m ≤ 10^9).
  
  Output
  
  For each test case, print a single integer — the answer to the problem.
  
  Example
  
  Input
  
  
  5
  3 5
  4 6
  3 2
  69 696
  123456 654321
  
  
  Output
  
  
  4
  3
  0
  640
  530866
  
  Note
  
  In the first test case, the sequence is 3 ⊕ 0, 3 ⊕ 1, 3 ⊕ 2, 3 ⊕ 3, 3 ⊕ 4, 3 ⊕ 5, or 3, 2, 1, 0, 7, 6. The smallest non-negative integer which isn't present in the sequence i. e. the \operatorname{MEX} of the sequence is 4.
  
  In the second test case, the sequence is 4 ⊕ 0, 4 ⊕ 1, 4 ⊕ 2, 4 ⊕ 3, 4 ⊕ 4, 4 ⊕ 5, 4 ⊕ 6, or 4, 5, 6, 7, 0, 1, 2. The smallest non-negative integer which isn't present in the sequence i. e. the \operatorname{MEX} of the sequence is 3.
  
  In the third test case, the sequence is 3 ⊕ 0, 3 ⊕ 1, 3 ⊕ 2, or 3, 2, 1. The smallest non-negative integer which isn't present in the sequence i. e. the \operatorname{MEX} of the sequence is 0.
solution: """RANK1ZEN; 3966 PEAK; NA; FLEX SUPPORT: Zen, Bap; Battlenet ID -> Knuckles#11791"""
  # region ---------------------------------------------------------------------------|
  # MNNNNNNNNNNNNNNNNMNho///++//+oooooossssssssssssysssooyyyyyso+//++//shNNNNNNNNNNNNNM
  # MNNNNNNNNNNNNNNMNy////////++++oooooooooossssssssoosssssysyyysoossss+/oshNNNNNNNNNNM
  # MNNNNNNNNNNNNMNs///////+oooooo++++oooooooooooso+ossssssssssssssssssss++soymMNNNNNNM
  # MNNNNNNNNNNNMd/:-//+//shNNmhsoo+++++++++ooooo++oooooooooossssssssssssso+ooosmNNNNNM
  # MNNNNNNNNNNMh::://+/+ymMMMMmhsoso+++++++++o+/+ooooooooooooooooooooossso++o+++hMNNNM
  # MNNNNNNNNNMy//-:/+/osmMMMMNhssyshNdssoooo++:++++++++++oooooooooooooooooo++-++/sMMNM
  # MNNNNNNNNMd:/:///+/ohNMMMNhsohyyNMNNNdhhs+:++++++++++++++++++++ooooooooo/+.o+:/+NNM
  # MNNNNNNNMm/:/-///++ooshmmhs+sysdMMMMNdMMd/+++++ooo++++++++++++++++++++++::-++/:/sNM
  # MNNNNNNMN/://-+++++++++oo+//yosNMNMNmNMNo/o/oshNmhyoo+++++++++++++++++++/-/+++:/:sM
  # MNNNNNMNo://-/+++++:/+++++//++osyhmdhMNs/o/+shMMMMmsooooyo++/+++++++++++://+++://oM
  # MNNNNNMs:///:/++++//++-/+/:++++++ooooyo++o-oyNNMMmysooymmso/+shysyyysooo+/++o+/-s+M
  # MNNNNMd:///+:/++++-++:`++:/++++//++++++:+-/oyhsmys+oohmyo++:sNMdmMMNNysy+-ohNs+-myM
  # MNNNMN::///+-:+++:.+/``++/++++++++++++:+/`+++oo/:/++oyo+oy+odNddMMMMmyyh:-sdMh/odyN
  # MNNNNo:///++-:+o/`::```++/+++++++++++//+-.o++:-:/++/+/+ymo/+ossyyhdhssy+.:ohhd/sy+M
  # MMNMh-///+++--oo:`/````++-+++++++++++-o/`/+:.:/+++//+hmNo/++++++ooooooo-`/+o++/++-M
  # MMMN/:///+++-.o/````-s:+/:++++++++++/++`.:.-/++++/+sdmmo/+++++++++++++: -+++++////M
  # MMMh:///++++-`+:```/dN+/::++++++++++++:``.+ooo++ohNMNm++oooooooo+++++o+ :++++/-//oM
  # MMd:/-/+++++-`/.``:hmm//./+++++++++o/o..:osoooymmdddmoooooooooooooo+oms.+++++////+M
  # MMo// -+++++:`.`` dNddo-.:+++++++++++--/soo:.--::ymh+ssssssssssooo+sNN/++++++++/-dM
  # Md/// `/+++o/```` dMddN.-:++++++++++/`/o/+:``-:-`/ooyssssssssssssoodmMo++++++++//NM
  # M/:// `-+oooo.``` oMNMM+--/+++++++++/:yd-``.`-+o+hoyyoosyyyyyyys:+o+o++o//+++++/hMM
  # m++:/```:oooo/````.dmNNm/-/+++++++//+dhy::ohs:/hysyosyyyyyyyyys:----:-/o/ooo++/-mMM
  # s:++//```/oooo-  ``yNmdm:-/++++++////MMNmdhoys+ssssyyyyyysoysss:-.odd/o+/+oo++-+MMM
  # s`:++/````:oooo. ```:hNNh-/++++++//:hNNNMMNMdsossyyyyyyss+osdM/o/:yNyoo///ooo/.MMNM
  # d `-++/-```:+oo+-`````-+ds/++++++//-mMMMNNhs+syyysysyys+osdMMNyoshdh/+/o:ooo+.+MMNM
  # M/` `-/+/-``.:ooo-```````s:++++++++/mNdhsoossssyyhyo/-+hmMMMMNNNNNNo//+.:oo++ oMMNM
  # MMo``:..-//-.`-+oo:.`````/+++++++++:ooossyhyyyo+:-:ohNMmMMMMMNmNNNh:/:` :oo/: mMMNM
  # MMMh.oMh+``.-:-.-/o+-````mh/+++++++:++++/:--:+syhmMMMMMNMMMMMMMMMo-.//``+oo:`-MMNNM
  # MMMMh-omNd+````..`./+/.`hMMs+++++++/dmmmmNMMNNMMMMMMMMMMMMMMMMms:`` :/..+oo: yMNNNM
  # MNNNMN/``..``````````.-.+dNy-oooooo/o+s++sNMMNmNMMmmNMMMMMMMmo-   ``-/.-oo+- yMNNNM
  # MNNNNMMNdy-``````..``````-+o/+ooooo/++///:`:yMMMMMMMMMMMMds/`/++/````o--o++- MMNNNM
  # MMNNMMMMMN:`........-:+oyssoo+ssssss:ooo+/+:`:mMMMMMNho/.````+ooohd+//:+ooo-/MMMMMM
  # MMMMMMMMMMs.-...-.-osyyyyysdMhshhhhhossssssdh-.ss+/-.``----.sdhy+mMMMsosssy:sMMMMMM
  # endregion ------------------------------------------------------------------------|
  # region ---------------------------------------------------------------------------|
  from sys import stdin, stdout
  from bisect import bisect_left, bisect_right
  from math import ceil, floor, log, sqrt
  from collections import Counter, deque
  from heapq import heappush, heappop, heapify
  from itertools import permutations, product
  def re(): return stdin.readline().rstrip()
  def mapi(): return map(int, re().split())
  def veci(): return list(map(int, re().split()))
  mod = 1000000007
  # endregion ------------------------------------------------------------------------|
  
  def solve(n, m):
      ans = 0
      for i in range(32, -1, -1):
          if n >= m: break
          if (m >> i) & 1 and not (n >> i) & 1: 
              n |= 1 << i
              ans |= 1 << i
      return ans
  
  
  # print(solve(69, 696 + 1))
  
  for t in range(int(re())):
      n, m = mapi()
      print(solve(n, m + 1))
  