#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, a[10], min_value = 1005, ans;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    if (a[i] < min_value) min_value = a[i], ans = i;
  }
  if (n < 2 || (n == 2 && a[0] == a[1]))
    cout << "-1\n";
  else
    cout << "1\n" << ans + 1 << '\n';
  return 0;
}
