#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  vector<int> v(n);
  for (size_t i = 0; i < n; i++) {
    cin >> v[i];
  }
  int ans = INT_MAX;
  int bcur = 0;
  int mask = 0;
  for (int i = 0; i < (1 << n); i++) {
    int sum1 = 0, sum2 = 0;
    int cur = 0;
    for (size_t j = 0; j < n; j++) {
      if ((1 << j) & i) {
        sum1 += v[j];
        cur++;
      } else
        sum2 += v[j];
    }
    if (sum1 != 0 && sum2 != 0 && sum1 != sum2) {
      if (abs(sum1 - sum2) < ans) {
        ans = abs(sum1 - sum2);
        mask = i;
        bcur = cur;
      }
    }
  }
  if (ans == INT_MAX) {
    cout << -1;
    return 0;
  }
  cout << bcur << "\n";
  for (size_t i = 0; i < n; i++) {
    if (mask & (1 << i)) cout << i + 1 << " ";
  }
}
