#include <bits/stdc++.h>
using namespace std;
const int MX = 1e5 + 9;
int n, a[MX], sum;
void dp(int x, int y, int sum1, int sum2) {
  if ((x | y) == (1 << n) - 1) {
    if (!x || !y) return;
    if (sum1 != sum2) {
      cout << __builtin_popcount(x) << endl;
      for (int i = 0; i < n; i++) {
        if (x & (1 << i)) cout << i + 1 << " ";
      }
      exit(0);
    }
  }
  for (int i = 0; i < n; i++) {
    if ((x & (1 << i)) || (y & (1 << i))) continue;
    dp(x | (1 << i), y, sum1 + a[i], sum2);
    dp(x, y | (1 << i), sum1, a[i] + sum2);
  }
}
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    sum += a[i];
  }
  dp(0, 0, 0, 0);
  puts("-1");
}
