#include <bits/stdc++.h>
int a[1005];
int main() {
  int n, sum = 0, min = 0xfffffff, t;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
    sum += a[i];
    if (min > a[i]) {
      min = a[i], t = i;
    }
  }
  if (n == 1)
    printf("-1\n");
  else {
    if (min == (sum - min))
      printf("-1\n");
    else {
      printf("1\n%d\n", t);
    }
  }
  return 0;
}
