#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n], b[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    b[i] = a[i];
  }
  if (n == 1)
    cout << -1;
  else {
    sort(b, b + n);
    int G = b[0];
    int s = accumulate(a, a + n, 0);
    if (s - G == G)
      cout << -1;
    else {
      cout << 1 << endl;
      auto it = find(a, a + n, G);
      int res = it - a;
      cout << res + 1;
    }
  }
  return 0;
}
