#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e6 + 9;
set<int> ist;
map<string, int> msi;
map<string, string> mss;
map<int, string> mis;
map<int, int> mii;
pair<int, int> pii;
vector<int> v;
vector<pair<int, int> > vv;
int cc[] = {1, -1, 0, 0};
int rr[] = {0, 0, 1, -1};
void BIRTH_MONTH() {
  int t;
  int n;
  cin >> n;
  int ahm[n];
  set<int> st;
  int mn = 1000000;
  int ans = 0;
  for (int i = 0; i < n; i++) {
    cin >> ahm[i];
    if (ahm[i] < mn) {
      mn = ahm[i];
      ans = i + 1;
    }
    st.insert(ahm[i]);
  }
  if (st.size() == 1) {
    if (n > 2) {
      cout << 1 << endl;
      cout << ans << endl;
    } else {
      cout << -1 << endl;
    }
  } else {
    cout << 1 << endl;
    cout << ans << endl;
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  BIRTH_MONTH();
  return 0;
}
