// clang-format off
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <bitset>
#include <vector>
#include <algorithm>
#include <random>
#include <map>
#include <string>
#include <set>
#include <deque>
#include <cassert>

const int N = 2e5+7, A = 26, C = 2;
using namespace std;
int n, k;

int a[N];
bool taken[N];
vector<pair<int, int> > ans;

void neutralize(int l, int r) {
    for (int i = l; i < r; i+=2) {
        if (a[i] == a[i + 1]) {
            ans.push_back({ i,i + 1 });
        }
        else {
            ans.push_back({ i,i });
            ans.push_back({ i + 1,i + 1 });
        }
    }
}

void toP(int l, int r) {
    for (int i = l; i <= r; i++) {
        if (a[i] == 1) {
            ans.push_back({ i,i });
            if (i != l) {
                neutralize(l, i - 1);
            }
            if (i != r) {
                neutralize(i + 1, r);
            }
            return;
        }
    }
    taken[l - 1] = 1;
    ans.push_back({ l - 1,r });
}

void toM(int l, int r) {
    for (int i = l; i <= r; i++) {
        if (a[i] == -1) {
            ans.push_back({ i,i });
            if (i != l) {
                neutralize(l, i - 1);
            }
            if (i != r) {
                neutralize(i + 1, r);
            }
            return;
        }
    }
    taken[l - 1] = 1;
    ans.push_back({ l - 1,r });
}

void solve() {
    ans.clear();
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        taken[i] = 0;
    }
    a[n] = 0;
    taken[n] = 0;
    int l = 0;
    vector<pair<int, int> > nec_otr, ch_otr;
    nec_otr.clear();
    ch_otr.clear();
    for (int i = 0; i <= n; i++) {
        if (a[i] == 0) {
            int len = i - l;
                if (len != 0) {
                    if (len % 2) {
                        nec_otr.push_back({ l, i - 1 });
                    }
                    else {
                        ch_otr.push_back({ l,i - 1 });
                    }
                }
            l = i + 1;
        }
    }
    if (nec_otr.size() % 2) {
        cout << "-1\n";
        return;
    }

    if (nec_otr.size() == 0 || a[nec_otr[0].first] == 1) {
        for (int i = 0; i < nec_otr.size() / 2; i++) {
            toP(nec_otr[i].first, nec_otr[i].second);
        }
        for (int i = nec_otr.size() / 2; i < nec_otr.size(); i++) {
            toM(nec_otr[i].first, nec_otr[i].second);
        }
    }
    else {
        for (int i = 0; i < nec_otr.size() / 2; i++) {
            toM(nec_otr[i].first, nec_otr[i].second);
        }
        for (int i = nec_otr.size() / 2; i < nec_otr.size(); i++) {
            toP(nec_otr[i].first, nec_otr[i].second);
        }
    }
    for (auto u : ch_otr) {
        neutralize(u.first, u.second);
    }
    for (int i = 0; i < n; i++) {
        if (a[i] == 0 && !taken[i]) {
            ans.push_back({ i,i });
        }
    }
    cout << ans.size() << '\n';
    sort(ans.begin(), ans.end());
    for (auto u : ans) {
        cout << u.first + 1 << " " << u.second + 1 << '\n';
    }
}

signed main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
#else
    std::ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}