#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef pair<double, double> pdd;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<vll> vvll;
typedef vector<vvll> vvvll;
typedef vector<pii> vpii;
typedef vector<vpii> vvpii;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;
typedef vector<pdd> vpdd;
typedef vector<vd> vvd;
#define yn(ans) printf("%s\n", (ans)?"Yes":"No");
#define YN(ans) printf("%s\n", (ans)?"YES":"NO");
    template<class T> bool chmax(T &a, T b) {
	if (a >= b) return false;
	a = b; return true;
}
template<class T> bool chmin(T &a, T b) {
	if (a <= b) return false;
	a = b; return true;
}
#define FOR(i, s, e, t) for ((i) = (s); (i) < (e); (i) += (t)) 
#define REP(i, e) for (int i = 0; i < (e); ++i) 
#define REP1(i, s, e) for (int i = (s); i < (e); ++i)
#define RREP(i, e) for (int i = (e); i >= 0; --i)
#define RREP1(i, e, s) for (int i = (e); i >= (s); --i)
#define all(v) v.begin(), v.end()
#define pb push_back
#define qb pop_back
#define pf push_front
#define qf pop_front
#define maxe max_element
#define mine min_element
ll inf = 1e18;
#define DEBUG printf("%d\n", __LINE__); fflush(stdout);
template<class T> void print(vector<T> &v, bool withSize = false) {
	if (withSize) cout << v.size() << endl;
	REP(i, v.size()) cout << v[i] << " "; 
	cout << endl;
}
mt19937_64 rng((unsigned int) chrono::steady_clock::now().time_since_epoch().count());

int __FAST_IO__ = []() {
	std::ios::sync_with_stdio(0);
	std::cin.tie(0);
	std::cout.tie(0);
	return 0;
}();

#define TESTS int t; cin >> t; while (t--)
#define TEST 
int main() {
    int N;
    cin >> N;
    vll v(N);
    REP(i, N) cin >> v[i];
    auto it = find(all(v), 0);
    if (it != v.end()) {
        printf("1\n%d\n", it - v.begin() + 1);
        return 0;
    }
    
    vll base, q;
    REP(i, N) {
        int j = 0;
        ll x = v[i];
        ll mask = 1ll << i;
        while (x > 0 && j < base.size()) {
            int a = __lg(x), b = __lg(base[j]);
            if (a > b) break;
            else if (a == b) x ^= base[j], mask ^= q[j];
            j++;
        }
        if (x == 0) {
            printf("%d\n", __builtin_popcountll(mask));
            REP(j, 63) {
                if (mask >> j & 1) printf("%d ", j + 1);
            }
            return 0;
        } 
        
        base.insert(base.begin() + j, x);
        q.insert(q.begin() + j, mask);
    }
    printf("-1\n");
    
    return 0;
}