#include <bits/stdc++.h>
using namespace std;
const int N = (int)1e3 + 4;
map<int, pair<int, int> > m;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int n, i, k, m = 1000000007, ans = 0;
  cin >> n;
  long long int a[n];
  if (n == 1) {
    cout << -1;
    return 0;
  }
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] < m) {
      m = a[i];
      ans = i + 1;
    }
  }
  if (n == 2 && a[0] == a[1]) {
    cout << -1;
    return 0;
  }
  sort(a, a + n);
  cout << 1 << endl << ans;
  return 0;
}
