#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n];
  fill(a, a + n, 0);
  int sum = 0;
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  int min1 = a[0];
  int ind = 0;
  for (int i = 0; i < n; ++i) {
    if (a[i] < min1) {
      min1 = a[i];
      ind = i;
    }
  }
  if (n == 1) {
    printf("-1");
    return 0;
  }
  if (n == 2) {
    if (a[0] == a[1])
      printf("-1");
    else
      printf("1\n2");
    return 0;
  } else {
    printf("1\n%d", ind + 1);
  }
  return 0;
}
