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

int main() {
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        vector<int>a(n), ans;
        int cnt0 = 0;
        for (int i = 0; i < n; i++) {
            cin >> a[i];
            if (!a[i]) cnt0++;
        }
        int cnt1 = n - cnt0;
        if (cnt0 >= n / 2) {
            cout << cnt0 << '\n';
            for (int i = 0; i < cnt0; i++) cout << 0 << ' ';
        } else {
            cout << cnt1 - cnt1 % 2 << '\n';
            for (int i = 0; i < cnt1 - cnt1 % 2; i++) {
                cout << 1 << ' ';
            }
        }
        cout << '\n';
    }
    return 0;
}

#include <bits/stdc++.h>

using namespace std;

void solve() {
    int n;
    cin >> n;
    int a[n];
    int mi = 0;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        mi = (a[i] > a[mi] ? i : mi);
    }
    vector<int> b(n);
    b[0] = a[mi]; a[mi] = 0;
    int cg = b[0];
    for (int i = 1; i < n; i++) {
        int ci = 0, cans = 0;
        for (int j = 0; j < n; j++)
            if (a[j] && __gcd(a[j], cg) > cans) {
                cans = __gcd(a[j], cg);
                ci = j;
            }
        b[i] = a[ci];
        cg = cans;
        a[ci] = 0;
    }
    for (int i = 0; i < n; i++)
        cout << b[i] << ' ';
    cout << '\n';
}

int main() {
    int t;
    cin >> t;
    while (t--)
        solve();
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int ask(int x, int y) {
    cout << "? " << x + 1 << ' ' << y + 1 << endl;
    int z;
    cin >> z;
    return z;
}
int main() {
    int n;
    cin >> n;
    vector<int>ans(n, -1);
    int mx = 0;
    for (int i = 1; i < n; i++) {
        int a = ask(mx, i);
        int b = ask(i, mx);
        if (a > b) {
            ans[mx] = a;
            mx = i;
        } else {
            ans[i] = b;
        }
    }
    ans[mx] = n;
    cout << "! ";
    for (int i = 0; i < n; i++) cout << ans[i] << ' ';
    cout << endl;
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 1;
const int maxn = 3e5 + 1;
int h[maxn], dp[maxn], lge[maxn], lle[maxn], rge[maxn], rle[maxn];
vector<int>jumps[maxn];
int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> h[i];
        dp[i] = INF;
    }
    dp[0] = 0;
    vector<pair<int, int> >st;
    for (int i = 0; i < n; i++) { // the nearest greater from the left
        while (!st.empty() && st.back().first < h[i]) {
            st.pop_back();
        }
        if (st.empty()) lge[i] = -1;
        else lge[i] = st.back().second;
        st.push_back({h[i], i});
    }
    st.clear();
    for (int i = 0; i < n; i++) { // the nearest less from the left
        while (!st.empty() && st.back().first > h[i]) {
            st.pop_back();
        }
        if (st.empty()) lle[i] = -1;
        else lle[i] = st.back().second;
        st.push_back({h[i], i});
    }
    st.clear();
    for (int i = n - 1; i >= 0; i--) { // the nearest greater from the right
        while (!st.empty() && st.back().first < h[i]) {
            st.pop_back();
        }
        if (st.empty()) rge[i] = -1;
        else rge[i] = st.back().second;
        st.push_back({h[i], i});
    }
    st.clear();
    for (int i = n - 1; i >= 0; i--) { // the nearest less from the right
        while (!st.empty() && st.back().first > h[i]) {
            st.pop_back();
        }
        if (st.empty()) rle[i] = -1;
        else rle[i] = st.back().second;
        st.push_back({h[i], i});
    }
    st.clear();
    for (int i = 0; i < n; i++) {
        if (rle[i] != -1) jumps[i].push_back(rle[i]);
        if (rge[i] != -1) jumps[i].push_back(rge[i]);
        if (lle[i] != -1) jumps[lle[i]].push_back(i);
        if (lge[i] != -1) jumps[lge[i]].push_back(i);
    }
    for (int i = 0; i < n; i++) {
        for (int to : jumps[i]) {
            dp[to] = min(dp[to], dp[i] + 1);
        }
    }
    cout << dp[n - 1];
    return 0;
}

#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e6 + 1;

vector<int> bg[maxn], rg[maxn];
int b[maxn], r[maxn], d[maxn], col[maxn];
int n, m;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int u, v, t;
        cin >> u >> v >> t;
        --u; --v;
        if (!t) bg[v].push_back(u);
        else rg[v].push_back(u);
    }
    for (int i = 0; i < n; i++)
        d[i] = b[i] = r[i] = n;
    queue<int> q;
    q.push(n - 1);
    d[n - 1] = r[n - 1] = b[n - 1] = 0;
    while (!q.empty()) {
        int x = q.front();
        q.pop();
        for (auto to : bg[x]) {
            if (b[to] < n) continue;
            b[to] = d[x] + 1;
            if (max(b[to], r[to]) < n) {
                q.push(to);
                d[to] = max(b[to], r[to]);
            }
        }
        for (auto to : rg[x]) {
            if (r[to] < n) continue;
            r[to] = d[x] + 1;
            if (max(b[to], r[to]) < n) {
                q.push(to);
                d[to] = max(b[to], r[to]);
            }
        }
    }
    if (d[0] == n) cout << "-1\n";
    else cout << d[0] << '\n';
    for (int i = 0; i < n; i++) {
        if (b[i] > r[i]) col[i] = 0;
        else col[i] = 1;
        cout << col[i];
    }
    return 0;
}