A_XORwice.cpp

#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define vi vector<int>
#define vc vector<char>
#define pyes cout << "YES";
#define pno cout << "NO";
#define ff() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define MOD (int)(1e9 + 7)
#define MOD1 998244353
#define input(start, end, arr) { for(int i = start; i < end; ++i) cin >> arr[i]; }
#define f(i, x, n) for (int i = x; i < n; i++)
#define rf(i, x, n) for (int i = x; i >= n; i--)
#define sz(a) (int) a.size()
#define ppc __builtin_popcount
#define ppcll __builtin_popcountll
#define pi (3.141592653589)
#define INF 1e18
#define nl '\n'
//------------------------------------------------------------------------------------------------------------------
int mod_add(int a, int b, int m) {a = a % m; b = b % m; return (((a + b) % m) + m) % m;}
int mod_mul(int a, int b, int m) {a = a % m; b = b % m; return (((a * b) % m) + m) % m;}
int mod_sub(int a, int b, int m) {a = a % m; b = b % m; return (((a - b) % m) + m) % m;}

int expo(int a, int b, int mod) {int res = 1; while (b > 0) {if (b & 1)res = (res * a) % mod; a = (a * a) % mod; b = b >> 1;} return res;}

// To get All Prime Factors
vi primeFactorization(int n) {
    vi factorization;
    for (int d = 2; d * d <= n; d++) {
        while (n % d == 0) {
            factorization.push_back(d);
            n /= d;
        }
    }
    if (n > 1) {
        factorization.push_back(n);
    }
    return factorization;
}

// Sieve of Eratosthenes function
vi sieve(int limit) {
    vi primes;
    vector<bool> is_prime(limit + 1, true);
    is_prime[0] = is_prime[1] = false;
    for (int i = 2; i <= limit; i++) {
        if (is_prime[i]) {
            primes.push_back(i);
            for (int j = i * i; j <= limit; j += i) {
                is_prime[j] = false;
            }
        }
    }
    return primes;
}

void solve(){
    int a,b;
    cin>>a>>b;
    int ans = 0;
    for(int i=0; i < 32; i++){
        if((a & (1 << i)) == (b & (1 << i))){
            int t = 1 << i;
            ans |= t;
        }
    }
    cout<<abs(ans)-1;
}

int32_t main(){
    int tc;
    cin>>tc;
    while(tc--){
        solve();
        cout<<nl;
    }
}