#include <iostream>
#include <cmath>
#include <cstring>
using namespace std;
 
long long t, n, m, sum, ans, cnt[105], a[100005];
 
int main()
{
    cin >> t;
    for( long long wdnmd = 1; wdnmd <= t; wdnmd++ )
    {
        memset( cnt, 0, sizeof( cnt ) );
        memset( a, 0, sizeof( a ) );
        sum = 0;
        ans = 0;
        cin >> n >> m;
        for( long long i = 1; i <= m; i++ )
        {
            cin >> a[i];
            sum += a[i];
            long long tmp = log( a[i] ) / log( 2 );
            cnt[tmp]++;
        }
        if( sum < n )
        {
            cout << -1 << endl;
            continue;
        }
        for( long long i = 0; i <= ( long long ) log( n ) / log( 2 ) + 1; i++ )
        {
            if( ( n >> i ) & 1 )
            {
                if( cnt[i] )
                {
                    cnt[i]--;
                }
                else
                {
                    long long tmp = i;
                    while( !cnt[tmp] )
                    {
                        ans++;
                        cnt[tmp]++;
                        tmp++;
                    }
                    cnt[tmp]--;
                    continue;
                }
            }
            cnt[i + 1] += cnt[i] / 2;
        }
        cout << ans << endl;
    }
    return 0;
}

挺离谱的，C++11本地测试样例过了，CF上WA，换了C++17原来错的点过了后面又错。

希望各位神犇们帮助一下蒟蒻吧QAQ