#include <bits/stdc++.h>
using namespace std;
clock_t time_p = clock();
void aryanc403() {
  time_p = clock() - time_p;
  cerr << "Time Taken : " << (float)(time_p) / CLOCKS_PER_SEC << "\n";
}
int mini(int a[], int n) {
  int m = a[0];
  int k = 0;
  for (int i = 1; i < n; i++) {
    if (a[i] < m) {
      m = a[i];
      k = i;
    }
  }
  return k + 1;
}
int main() {
  int n;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  if (n == 1) {
    cout << -1;
  } else if (n == 2) {
    if (a[0] == a[1]) {
      cout << -1;
    } else {
      cout << 1 << endl << 1;
    }
  } else {
    cout << 1 << endl << mini(a, n);
  }
  return 0;
}
