///
///                            _ooOoo_
///                           o8888888o
///                           88" . "88
///                           (| -_- |)
///                           O\  =  /O
///                        ____/`---'\____
///                      .'  \\|     |//  `.
///                     /  \\|||  :  |||//  \
///                    /  _||||| -:- |||||-  \
///                    |   | \\\  -  /// |   |
///                    | \_|  ''\---/''  |   |
///                    \  .-\__  `-`  ___/-. /
///                  ___`. .'  /--.--\  `. . __
///               ."" '<  `.___\_<|>_/___.'  >'"".
///              | | :  `- \`.;`\ _ /`;.`/ - ` : | |
///              \  \ `-.   \_ __\ /__ _/   .-` /  /
///         ======`-.____`-.___\_____/___.-`____.-'======
///                            `=---='
///        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
///                      Buddha Bless, No Bug !
///
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <vector>
using namespace std;
#define MAXN 100010
#define ll long longint t, m;
ll k, ans_n;ll cal(ll n, int m)
{if(n < 1)return 0;for(ll i = n + 1;  ; i++)if(__gcd(n, i) == 1){m--;if(m == 0)return i - n;/// (i - n) = (f(n, m) - n) = d
        }
}int main()
{scanf("%d", &t);while(t--){scanf("%lld%d", &k, &m);ans_n = -1;for(int d = 1; d <= 1000; d++){if(cal(k ^ d, m) == d){if(ans_n == -1)ans_n = k ^ d;else if(ans_n > (d ^ k))/// ^ 运算的有优先度小于 <  >  ==  !=ans_n = k ^ d;}}printf("%lld\n", ans_n);}return 0;
}