#include <bits/stdc++.h>
using namespace std;
int64_t inf = 1000 * 1000 * 1000;
int64_t inf64 = inf * inf;
int64_t mod = 228228227;
int64_t nll = 0;
int64_t ans[100];
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cerr << fixed << setprecision(8);
  srand(time(0));
  auto START_TIME = chrono::high_resolution_clock::now();
  int32_t n;
  cin >> n;
  vector<pair<int32_t, int32_t> > a(n);
  for (int32_t i = 0; i < n; ++i) {
    cin >> a[i].first;
    a[i].second = i + 1;
  }
  if (n == 1)
    cout << -1;
  else {
    sort(a.begin(), a.end());
    int64_t sum = 0;
    for (int32_t i = 1; i < n; ++i) sum += a[i].first;
    if (sum != a[0].first)
      cout << 1 << endl << a[0].second;
    else
      cout << -1;
  }
  cerr << endl
       << chrono::duration<long double>(chrono::high_resolution_clock::now() -
                                        START_TIME)
              .count()
       << " sec.";
}
