#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vii> vvii;
typedef vector<vi> vvi;
typedef pair<double, double> dodo;
#define pb(x) push_back(x)
#define mp(x, y) make_pair(x, y)
int N, M;
bool dp[524288] = {0};
void func(int m) {
if (dp[m]) return;
dp[m] = true;
if (m == (m & -m)) return;
int t1 = m;
int t2 = t1 - (t1 & -t1);
while (true) {
if (t2 == (t2 & -t2)) return;
int x = m;
x -= (t1 & -t1);
int t3 = t2 - (t2 & -t2);
x -= (t3 & -t3);
func(x);
t1 = t2;
t2 = t3;
}
}
void pp() {
func((1<<N)-1);
//for (int i = 0; i < 10; i++) cerr << dp[i] << " ";
//cerr << endl;
}
int main(int argc, char **argv) {
ios_base::sync_with_stdio(0);
cin.tie(0);
int TC; cin >> TC;
for (int tc = 1; tc <= TC; tc++) {
cin >> N >> M;
if (tc == 1) pp();
int x = 0;
for (int i = 0; i < M; i++) {
int a; cin >> a;
x += (1<<(a-1));
}
if (dp[x]) {
cout << "0\n\n";
} else {
cout << "-1\n";
}
}
return 0;
}
