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

#define endl '\n'
#define optimize() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

void solve(){
    int n;
    cin>>n;
    int cnt0=0,cnt1 =0, cntn1=0;
    for(int i=0; i<n; i++){
        int x;
        cin>>x;
        if(x==0) cnt0++;
        else if(x==1) cnt1++;
        else cntn1++;
    }

    int result = 0;
    if(cntn1 >= 2*cnt1){
        result += cnt1;
        cntn1 -= (2*cnt1);
        cnt1 = 0;
        
        if(cntn1 >= 2*cnt0){
            cntn1 -= (2*cnt0);
            cnt0 = 0;
        }
        else{
            cntn1 =0;
            cnt0 =0;
        }
        result -= (cntn1/3);
    }
    else{
        result += cntn1/2;
        cnt1 -= cntn1/2;
        cntn1 %= 2;

        result += cnt1/3;
        cnt1 %= 3;

        if(!cnt0 and cntn1) result--;

    }
    cout<<result<<endl;
}

signed main(){
    // freopen("input.txt","r",stdin);
    // freopen("output.txt","w",stdout);
    optimize();

    ll t;
    cin>>t;
    for(ll i=1; i<=t; i++){
        solve();
    }
    return 0;
}