#include <iostream>
#include <iomanip>
#include <algorithm>
#include <bitset>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <cmath>
#include <time.h>
#include <random>
#include <string>
#include <cassert>
#include <vector>
#include <ostream>
#include <istream>
#include <stack>
#include <deque>
#include <queue>
#include <functional>

using namespace std;

#define int long long
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define pii pair<int, int>
#define ld long double

ostream& operator << (ostream &a, const vector<int> &b) {
    for (auto k : b) cout << k << " ";
    return a;
}

#ifdef LOCAL
    #define dbg(x) cout << #x << " : " << (x) << "\n";
    const int INF = 1e18;
    const int mlog = 20;
//    const int mod = 2600000069;
//    const int p = 10;
//    const ld PI = 3.1415926535;
#else
    #define dbg(x)
    const int INF = 1e18;
    const int mlog = 61;
//    const int mod = 2600000069;
//    const int p = 179;
//    const ld PI = 3.1415926535;
#endif

//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,sse3,sse4")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("fast-math")
//#pragma GCC target("avx2")
//#pragma GCC optimize("section-anchors")
//#pragma GCC optimize("profile-values,profile-reorder-functions,tracer")
//#pragma GCC optimize("vpt")s
//#pragma GCC optimize("rename-registers")
//#pragma GCC optimize("move-loop-invariants")
//#pragma GCC optimize("unswitch-loops")
//#pragma GCC optimize("function-sections")
//#pragma GCC optimize("data-sections")


void solve() {
    int n, m;
    cin >> n >> m;
    vector<int> a(m);
    vector<int> cnt(mlog, 0);
    for (int i = 0; i < m; i++) {
        cin >> a[i];
        cnt[log2(a[i])]++;
    }
//    dbg(cnt);
    for (int i = 0; i < mlog; i++) {
        if (((n >> i) & 1)) {
            if (cnt[i]) {
                n -= (1LL << i);
                cnt[i]--;
                continue;
            }
            vector<pii> take;
            int need = (1LL << i);
            for (int j = i - 1; j >= 0; j--) {
                if (!cnt[j]) continue;
                if (need <= cnt[j] * (1LL << j)) {
                    take.pb({j, need / (1LL << j)});
                    need -= ((need / (1LL << j)) * (1LL << j));
                } else {
                    take.pb({j, cnt[j]});
                    need -= (1LL << j) * cnt[j];
                }
            }
            if (need == 0) {
                for (auto k : take) {
                    cnt[k.first] -= k.second;
                }
                n -= (1LL << i);
            }
        }
    }
    int ans = 0;
    int lst = -1;
    for (int i = mlog - 1; i >= 0; i--) {
        if ((n >> i) & 1) {
            if (lst == -1) {
                for (int j = i + 1; j < mlog; j++) {
                    if (cnt[j]) {
                        lst = j;
                        break;
                    }
                }
            }
            if (lst == -1) {
                cout << "-1\n";
                return;
            }
            cnt[lst]--;
            cnt[i] += (1LL << lst) / (1LL << i) - 1;
            ans += lst - i;
//            lst = i;
        }
        if (cnt[i]) lst = i;
    }
    cout << ans << "\n";
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int q = 1;
    cin >> q;
    while (q--) solve();
}
/*
10 3
1 32 1
-> 2
*/