#include<bits/stdc++.h>
using namespace std;
const int N = 1024;
void solve()
{
    int n, m; cin >> n >> m;
    vector<int> v(n + 1), w(n + 1);
    for(int i = 1; i <= n; i++) cin >> v[i] >> w[i];
    vector<bitset<N> > f(N);
    f[0][0] = 1;
    for(int i = 1; i <= n; i++)
        for(int k = 0; k < N; k++)
            f[k] |= f[k ^ w[i]] << v[i];
    for(int i = N - 1; i >= 0; i--)
        if(f[i][m])
        {
            cout << i << '\n';
            return;
        }
	cout << "-1\n";
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int t;
	cin >> t;
	while (t--)
		solve();
}