#include <bits/stdc++.h>
using namespace std;
const int N = 1e3 + 5, MOD = 1e9 + 7;
int ar[] = {1, -1, 0, 0}, ac[] = {0, 0, 1, -1};
int main() {
  int n, m;
  scanf("%d", &n);
  int a[n];
  int mn = 1e9;
  int id = 0;
  for (int i = 0; i < n; i++) {
    scanf("%d", a + i);
    if (mn > a[i]) {
      mn = a[i];
      id = i + 1;
    }
  }
  if (n < 2) return cout << "-1", 0;
  if (n == 2 && a[0] == a[1]) return cout << "-1", 0;
  printf("1\n%d", id);
  ;
  return 0;
}
