#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:256000000")
using namespace std;
const int INF = (int)(1e9 + 1e6);
const long long LINF = (long long)(4e18);
const double EPS = 1e-14;
mt19937 ggen;
void solve();
int main() {
  iostream::sync_with_stdio(false);
  cin.tie(0);
  ggen = mt19937(1337);
  solve();
}
void solve() {
  int n;
  cin >> n;
  vector<pair<int, int> > a(n);
  for (int i = 0; i < n; ++i) {
    cin >> a[i].first;
    a[i].second = i;
  }
  sort((a).begin(), (a).end());
  if (n == 1) {
    cout << -1;
    return;
  }
  if (n == 2) {
    if (a[0].first == a[1].first) {
      cout << -1;
      return;
    }
  }
  cout << n - 1;
  cout << endl;
  for (int i = n - 1; i > 0; --i) {
    cout << a[i].second + 1 << " ";
  }
}
