codeforces_a_xorwice.cpp

#include<bits/stdc++.h>
#define ll long long
#define testcase(t) ll t; cin>>t; while(t--)
using namespace std;

void quickstart(){
	#ifndef ONLINE_JUDGE
		freopen("input.txt","r",stdin);
		freopen("output.txt","w",stdout);
	#endif
	ios_base::sync_with_stdio(0);
}

int main(){
	quickstart();
	testcase(t){
		ll a, b;
		cin >> a >> b;
		ll ans = a^b;
		cout << ans << endl;
	}
}