#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long T, s, pozw, x, k, n, mi, m, qqq, a, b, z, kot, t, w, g, h, sum, f,
      poz, kry, kol, ot, i, q, ma, kolv, p, l, r, y, za, zu, sum1;
  vector<long long> pod, dup, vov, ne, st(31);
  cin >> t;
  st[0] = 1;
  for (i = 1; i <= 30; i = i + 1) {
    st[i] = 2 * st[i - 1];
  }
  for (qqq = 0; qqq < t; qqq = qqq + 1) {
    cin >> a >> b;
    x = 0;
    for (i = 0; i <= 30; i = i + 1) {
      if (((a & st[i]) > 0) && ((b & st[i]) > 0)) {
        x = x + st[i];
      }
    }
    p = (a ^ x) + (b ^ x);
    cout << p << "\n";
  }
  return 0;
}
