#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e3 + 30;
struct a {
  int num;
  int x;
} bb[maxn];
bool cmp(a a1, a a2) { return a1.num < a2.num; };
int main() {
  int n, i;
  scanf("%d", &n);
  for (i = 0; i < n; i++) scanf("%d", &bb[i].num), bb[i].x = i + 1;
  if (n == 1 || n == 2 && bb[0].num == bb[1].num) {
    puts("-1");
    return 0;
  }
  sort(bb, bb + n, cmp);
  printf("1\n%d\n", bb[0].x);
  return 0;
}
