#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, n, x, s = 0, c = 0, j;
  cin >> n;
  int a[100];
  for (i = 0; i < n; i++) {
    cin >> a[i];
    s += a[i];
  }
  if (n == 1) {
    cout << -1;
    return 0;
  }
  for (i = 0; i < n; i++) {
    x = s - a[i];
    if (x != a[i]) {
      c = 1;
      break;
    }
  }
  if (c == 1)
    cout << 1 << "\n" << i + 1;
  else
    cout << -1;
}
