#include <bits/stdc++.h>
using namespace std;
int elements[10010];
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", &elements[i]);
  if (n != 1) {
    for (int i = 0; i < n; i++) {
      int s1 = elements[i], s2 = 0;
      for (int j = 0; j < n; j++) {
        if (i == j) continue;
        s2 += elements[j];
      }
      if (s1 != s2 and s2 != 0) {
        printf("1\n%d\n", i + 1);
        return 0;
      }
    }
    printf("-1\n");
  } else
    printf("-1\n");
  return 0;
}
