#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
const double PI = acos(-1.0);
int m, n, x, t, y, a[200005], k, l, r, z, all, ans, b[200005];
char c;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long qpow(long long a, long long n, long long p = (long long)1000000007) {
  long long r = 1 % p;
  for (a %= p; n; a = a * a % p, n >>= 1)
    if (n & 1) r = r * a % p;
  return r;
}
long long inv(long long x, long long p = (long long)1000000007) {
  return x <= 1 ? 1 : inv(p % x, p) * (p - p / x) % p;
}
void init() {}
void solve() {
  scanf("%d%d", &x, &y);
  printf("%d\n", x ^ y);
}
int main() {
  int T;
  T = 1;
  scanf("%d", &T);
  for (int i = 1; i <= T; i++) {
    init();
    solve();
  }
  return 0;
}
