#include <bits/stdc++.h>
using namespace std;
bool compare(const pair<int64_t, int64_t> &a, const pair<int64_t, int64_t> &b) {
  return (a.second > b.second);
}
bool comparell(const int64_t &a, const int64_t &b) { return a > b; }
int64_t modularExponentiation(int64_t a, int64_t n) {
  int64_t ans = 1;
  a %= 1000000007;
  while (n) {
    if (n % 2) {
      ans = (ans * a) % 1000000007;
    }
    a = (a * a) % 1000000007;
    n /= 2;
  }
  return ans;
}
void solve() {
  int64_t n;
  cin >> n;
  if (n == 1) {
    cout << -1 << endl;
    return;
  } else if (n == 2) {
    int64_t x, y;
    cin >> x >> y;
    if (x == y) {
      cout << -1 << endl;
    } else {
      cout << 1 << endl << 1 << endl;
    }
    return;
  } else {
    int64_t x;
    int64_t ans = 100000;
    int64_t ind = -1;
    for (int64_t i = 0; i < int64_t(n); i++) {
      cin >> x;
      if (x < ans) {
        ans = x;
        ind = i + 1;
      }
    }
    cout << 1 << endl << ind << endl;
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  ;
  solve();
}
