#include <bits/stdc++.h>
using namespace std;
const long long int INF = 9223372036854775807;
const long long int mod = 998244353;
long long int max3(long long int a, long long int b, long long int c) {
  return max(c, max(a, b));
}
long long int min3(long long int a, long long int b, long long int c) {
  return min(a, min(b, c));
}
long long int power(long long int x, long long int y, long long int mod1) {
  long long int res = 1;
  while (y > 0) {
    if (y & 1) res = (res * x) % mod1;
    y = y >> 1;
    x = (x * x) % mod1;
  }
  return res;
}
long long int logg(long long int a) {
  long long int x = 0;
  while (a > 1) {
    x++;
    a /= 2;
  }
  return x;
}
long long int gcd(long long int a, long long int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long int abso(long long int x) {
  if (x < 0) {
    return -x;
  }
  return x;
}
long long int ceiling(long long int a, long long int b) {
  if (a % b == 0) {
    return a / b;
  } else {
    return a / b + 1;
  }
}
long long int modinv(long long int x, long long int p) {
  return power(x, p - 2, p);
}
struct point {
  long long int x;
  long long int y;
};
long long int cross(point a, point b) { return a.x * b.y - b.x * a.y; }
bool ccw1(point p1, point p2) {
  if (cross(p1, p2) > 0) {
    return true;
  } else {
    return false;
  }
}
bool comp(point p1, point p2) {
  if (p1.x < p2.x) {
    return true;
  } else {
    if (p1.x > p2.x) {
      return false;
    } else {
      if (p1.y <= p2.y) {
        return true;
      }
      return false;
    }
  }
}
long long ccw(point p1, point p2, point p3) {
  long long int val =
      (p2.y - p1.y) * (p3.x - p2.x) - (p2.x - p1.x) * (p3.y - p2.y);
  return val;
}
void ccw_sort(vector<point> &v) {
  vector<point> v1, v2;
  for (int i = 0; i < v.size(); i++) {
    if (v[i].y > 0) {
      v1.push_back(v[i]);
    } else {
      v2.push_back(v[i]);
    }
  }
  sort(v1.begin(), v1.end(), ccw1);
  sort(v2.begin(), v2.end(), ccw1);
  for (int i = 0; i < v2.size(); i++) {
    v1.push_back(v2[i]);
  }
  v = v1;
}
void dfs(int i) {}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int t;
  cin >> t;
  while (t--) {
    long long int n, m;
    cin >> n >> m;
    vector<long long int> a(m);
    long long int tot = 0;
    long long int ans = 0;
    for (int i = 0; i < m; i++) {
      cin >> a[i];
      tot += a[i];
    }
    vector<long long int> avail(63);
    for (int i = 0; i < m; i++) {
      for (long long int j = 0; j < 63; j++) {
        if ((a[i] & ((long long int)1 << (long long int)j))) {
          avail[j]++;
        }
      }
    }
    vector<long long int> req(63);
    for (long long int j = 0; j < 63; j++) {
      if (n & ((long long int)1 << (long long int)j)) {
        req[j]++;
      }
    }
    if (tot < n) {
      cout << -1 << endl;
    } else {
      bool c = true;
      long long int leftover = 0;
      for (long long int i = 0; i <= 62; i++) {
        leftover += avail[i] * ((long long int)1 << i);
        if (leftover >= (req[i] * ((long long int)1 << i))) {
          leftover -= (req[i] * ((long long int)1 << i));
        } else {
          long long int sm = -1;
          for (long long int j = i + 1; j <= 62; j++) {
            if (avail[j]) {
              sm = j;
              break;
            }
          }
          avail[sm]--;
          for (long long int j = i; j <= sm - 1; j++) {
            ans++;
            avail[j]++;
          }
          if (sm == -1) {
            c = false;
            break;
          } else {
            leftover += ((long long int)1 << i);
          }
        }
      }
      if (c) {
        cout << ans << endl;
      } else {
        cout << -1 << endl;
      }
    }
  }
}
