/*
* Author: Geeza
*/
#include <bits/stdc++.h>
#define ld long double
#define ll long long
#define pb push_back
#define fin(a, n) for(int i = a; i < n; i++)
#define fjn(a, n) for(int j = a; j < n; j++)
#define all(a) a.begin(),a.end()
#define allr(a) a.rbegin(),a.rend()
#define FAST ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr)
using namespace std;
const double PI = acos(-1);
const int N = 2e3+10;
const ll oo = 0x3f3f3f3f3f3f3f3f;
const int MOD = 1000000007, inf = 1e6;
string di[] = {"D","L", "U", "R", "UL", "UR", "DL", "DR"};
int dx[] = {+1, +0, +0, -1, -1, -1, +1, +1};
int dy[] = {+0, -1, +1, +0, -1, +1, -1, +1};
char dc[] = {'D', 'L', 'R', 'U'};
void solve() {
int a, b; cin >> a >> b;
a ^= b;
cout << a << "\n";
}
int main() {
FAST;
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
int tt = 1; cin >> tt;
while (tt--) {
solve();
//cout << "Case #" << c++ << ": ";
}
return 0;
}
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