#include <bits/stdc++.h>
using namespace std;
const int INF = 1000 * 1000 * 1000;
vector<string> ans;
void drop(string s, long long n) {
  if (s.size() == n) {
    ans.push_back(s);
    return;
  }
  drop(s + '0', n);
  drop(s + '1', n);
}
bool p(string &s, vector<long long> &arr) {
  long long sum1 = 0, sum2 = 0;
  for (long long i = 0; i < arr.size(); i++) {
    if (s[i] == '0') {
      sum1 += arr[i];
    } else {
      sum2 += arr[i];
    }
  }
  if (sum1 != sum2 && sum1 != 0 && sum2 != 0) {
    return true;
  }
  return false;
}
int main() {
  bool sw = false;
  long long n;
  cin >> n;
  vector<long long> arr(n);
  for (long long i = 0; i < n; i++) {
    cin >> arr[i];
  }
  if (n == 1 || (n == 2 && arr[0] == arr[1])) {
    cout << -1 << endl;
    return 0;
  }
  drop("", n);
  for (long long i = 0; i < ans.size(); i++) {
    if (p(ans[i], arr)) {
      sw = true;
      long long sum = 0;
      for (long long j = 0; j < ans[i].size(); j++) {
        if (ans[i][j] == '1') {
          sum++;
        }
      }
      cout << sum << endl;
      for (long long j = 0; j < ans[i].size(); j++) {
        if (ans[i][j] == '1') {
          cout << j + 1 << endl;
        }
      }
      break;
    }
  }
  if (!sw) {
    cout << -1 << endl;
  }
  return 0;
}
