#include <bits/stdc++.h>
#pragma GCC optimize(2)
using namespace std;
const double pai = acos(-1.0);
const int maxn = 1e6 + 10;
const int mod = 998244353;
const double eps = 1e-9;
const int N = 5e3 + 10;
inline int read() {
  int k = 0, f = 1;
  char c = getchar();
  while (!isdigit(c)) {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (isdigit(c)) k = (k << 1) + (k << 3) + c - 48, c = getchar();
  return k * f;
}
long long n, m, mul[40];
int t;
int main() {
  mul[0] = 1;
  for (int i = 1; i <= 32; i++) mul[i] = mul[i - 1] * 2;
  scanf("%d", &t);
  while (t--) {
    scanf("%lld%lld", &n, &m);
    long long sum = 0, p = m + 1;
    for (int i = 32; i >= 0; i--) {
      long long x = n & (1ll << i), y = p & (1ll << i);
      if (x && !y) break;
      if (y && !x) sum += mul[i];
    }
    printf("%lld\n", sum);
  }
  return 0;
}
