#include <bits/stdc++.h>
int n, m, arr[20], sum = 0, ans, pac[200], k = 0;
using namespace std;
bool sol(int seq, int val, int sm) {
  if (sm != 0 && sm != sum - sm && sum - sm != 0) {
    ans = val;
    return true;
  }
  if (seq == n) return false;
  for (int i = seq; i < n; i++) {
    if (sol(seq + 1, val + 1, sm + arr[i])) {
      pac[k++] = i;
      return true;
    }
  }
  return false;
}
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", &arr[i]);
  for (int i = 0; i < n; i++) sum += arr[i];
  bool s = sol(0, 0, 0);
  sort(pac, pac + k);
  if (s) {
    printf("%d\n", ans);
    for (int i = 0; i < k; i++) printf("%d ", pac[i] + 1);
  } else
    printf("-1");
  return 0;
}
