#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int sum = 0;
  int a[20];
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    sum += a[i];
  }
  int j;
  int minn = 1010;
  if (n == 1)
    cout << "-1" << endl;
  else {
    for (int i = 1; i <= n; i++) {
      if (a[i] < minn) {
        minn = a[i];
        j = i;
      }
    }
    if (minn == sum - minn)
      cout << "-1" << endl;
    else
      cout << "1" << endl << j << endl;
  }
  return 0;
}
