#include <iostream>
#include <vector>
#include <cstring>
#include <algorithm>
#include <stack>
#include <fstream>
using namespace std;
typedef long long ll;
string to_binary(long long x) {
    string r = "";
    while(x) {
        r += (x % 2) + '0';
        x /= 2;
    }
    reverse(r.begin(), r.end());
    return r;
}
int main() {
    ll numa, numb;
    int n;
    cin >> n;

    for(int i = 0; i < n; i++) {
        cin >> numa >> numb;
        string a = to_binary(numa);
        string b = to_binary(numb);

        if(a.size() != b.size()) {
            cout << 0 << endl;
            continue;
        }
        string tmp = "";
        for(int i = 0; i < a.size(); i++) {
            if(a[i] == b[i]) {
                tmp += a[i];
            }
            else {
                break;
            }
        }
        while(tmp.size() < a.size()) {
            tmp += "0";
        }
        long long result = 0;
        long long stepen = (int) a.size() - 1;
        for(int j = 0; j < tmp.size(); j++) {
            if(tmp[j] == '1') {
                result |= (1LL << stepen);
            }
            stepen--;
        }
        cout << result << endl;
    }
    return 0;
}