#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, ind;
  int a[116];
  int ans = 10005;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (ans > a[i]) {
      ans = a[i];
      ind = i + 1;
    }
  }
  if (n == 1)
    puts("-1");
  else if (n == 2) {
    if (a[0] == a[1])
      puts("-1");
    else
      cout << 1 << endl << ind;
  } else {
    cout << 1 << endl << ind;
  }
  return 0;
}
