#include <bits/stdc++.h>
using namespace std;
const int N = 100;
int ara[N];
int main() {
  int n = 0;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    scanf("%d", ara + i);
  }
  if (n == 1)
    puts("-1");
  else if (n == 2 && ara[0] == ara[1])
    puts("-1");
  else {
    int mn = 10000;
    int nm = 0;
    for (int i = 0; i < n; ++i) {
      if (ara[i] < mn) {
        mn = ara[i];
        nm = i;
      }
    }
    ++nm;
    printf("1\n%d\n", nm);
  }
  return 0;
}
