#include <bits/stdc++.h>
const long long N = 1000006;
using namespace std;
const long long MOD = 1000000007LL;
template <typename T>
T gcd(T a, T b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
template <typename T>
T power(T x, T y, long long m = MOD) {
  T ans = 1;
  while (y > 0) {
    if (y & 1LL) ans = (ans * x) % m;
    y >>= 1LL;
    x = (x * x) % m;
  }
  return ans % m;
}
int32_t main() {
  long long n;
  cin >> n;
  if (n <= 1) {
    cout << "-1";
    return 0;
  }
  vector<long long> v(n);
  for (long long(i) = (0); i < (n); i++) cin >> v[i];
  for (long long i = 1; i < (1 << n); i++) {
    vector<long long> a, b;
    for (long long j = 0; j < n; j++) {
      if (i & (1 << j))
        a.emplace_back(j);
      else
        b.emplace_back(j);
    }
    if (a.empty() || b.empty()) continue;
    long long as = 0, bs = 0;
    for (auto i : a) as += v[i];
    for (auto i : b) bs += v[i];
    if (as == bs) continue;
    cout << a.size() << '\n';
    for (auto i : a) {
      cout << i + 1 << " ";
    }
    return 0;
  }
  cout << "-1";
}
