#include <bits/stdc++.h>
using namespace std;
int n, k;
int a[11];
int tmpa[11];
int sum;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    tmpa[i] = a[i];
    sum += a[i];
  }
  sort(a, a + n);
  if (n == 1) {
    cout << -1 << endl;
  } else {
    if (n == 2 && a[0] == a[1]) {
      cout << -1 << endl;
    } else {
      cout << 1 << endl;
      for (int i = 0; i < n; i++) {
        if (tmpa[i] == a[0]) {
          cout << i + 1 << endl;
          break;
        }
      }
    }
  }
  return 0;
}
