#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long int n, i;
  cin >> n;
  long long int a[n];
  for (i = 0; i < n; i++) cin >> a[i];
  if (n == 1) {
    cout << -1;
    return;
  } else if (n == 2) {
    if (a[0] == a[1]) {
      cout << -1;
      return;
    } else {
      cout << 1 << "\n";
      cout << 1;
      return;
    }
  }
  cout << 1 << "\n";
  long long int r = 1e9;
  for (i = 0; i < n; i++) r = min(r, a[i]);
  for (i = 0; i < n; i++)
    if (a[i] == r) break;
  cout << i + 1;
  return;
}
int main() {
  long long int t = 1;
  while (t--) solve();
  return 0;
}
