#include <bits/stdc++.h>
using namespace std;
const int MOD = 998244353;
const int INF = 1e18;
const int MAXN = 1e6 + 5;
const int T = 2500 + 3;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << fixed;
  cout.precision(10);
  setlocale(LC_ALL, "Russian");
  int i = 0, n, j, m, q;
  cin >> n;
  vector<int> a(n + 1);
  set<pair<int, int> > A;
  long long s = 0;
  for (i = 1; i <= n; i++) {
    cin >> a[i];
    s += a[i];
    A.insert({a[i], i});
  }
  int ind = A.begin()->second;
  if (n == 1 || a[ind] * 2 == s) {
    cout << -1;
    return 0;
  }
  cout << 1 << "\n" << ind;
  return 0;
}
