#include <bits/stdc++.h>
int main() {
  int n;
  scanf("%d", &n);
  int a[n], i;
  for (i = 0; i < n; i++) scanf("%d", &a[i]);
  if (n == 1 || (n == 2 && a[0] == a[1]))
    printf("-1");
  else if (n == 2)
    printf("1\n1");
  if (n > 2) {
    if (a[0] < a[1])
      printf("1\n1");
    else
      printf("1\n2");
  }
}
