#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define int long long
#define all(x) (x).begin(), (x).end()
#define f(i, n) for (int i = 0; i < n; i++)
#define trace(x) cerr << #x << ": " << x << '\n'
int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        int c0 = 0, c1 = 0, cm1 = 0, ans = 0;
        f(i, n)
        {
            int x;
            cin >> x;
            if (x == 0)
                c0++;
            else if (x == 1)
                c1++;
            else
                cm1++;
        }
        if (c1 + cm1 < 3)
        {
            cout << "0\n";
            continue;
        }
        while (cm1 >= 2 and c1)
        {
            cm1 -= 2;
            c1--;
            ans++;
        }
        while (cm1 >= 2 and c0)
        {
            cm1 -= 2;
            c0--;
        }
        while (cm1 and c0 >= 2)
        {
            cm1--;
            c0 -= 2;
        }
        while (cm1 and c1 >= 2)
        {
            cm1--;
            c1 -= 2;
            ans--;
        }
        // cout<<ans<<' '<<c0<<' '<<c1<<' '<<cm1<<'\n';
        while (c1 > 2)
        {
            c1 -= 3;
            ans++;
        }
        cout << ans << '\n';
    }
}