#include <bits/stdc++.h>
using namespace std;
long long pow_mod(long long x, long long y) {
  long long r = 1;
  for (; y; y >>= 1, x = (long long)x * x % 998244353)
    if (y & 1) r = (long long)r * x % 998244353;
  return r;
}
int main() {
  int n;
  cin >> n;
  if (n == 1) {
    cout << -1;
    return 0;
  } else if (n == 2) {
    int x, y;
    cin >> x >> y;
    if (x == y) {
      cout << -1;
      return 0;
    } else {
      cout << 1 << "\n" << 1;
    }
  } else {
    int x, y;
    cin >> x >> y;
    if (x <= y)
      cout << 1 << "\n" << 1;
    else
      cout << 1 << "\n" << 2;
  }
}
