#include <bits/stdc++.h>
using namespace std;
int val[15];
int main() {
  int N;
  scanf("%d", &N);
  if (N == 1) {
    printf("-1");
    return 0;
  }
  for (int i = 1; i <= N; i++) {
    scanf("%d", &val[i]);
  }
  if (N == 2) {
    if (val[1] == val[2]) {
      printf("-1");
      return 0;
    }
  }
  int k = min_element(val + 1, val + N + 1) - val;
  printf("%d\n", 1);
  printf("%d", k);
}
