#include <bits/stdc++.h>
using namespace std;
const long long MOD = (long long)(1e9 + 7);
long long modular(long long x) {
  x %= MOD;
  if (x < 0) x += MOD;
  return x;
}
const int MAXN = (int)(1e6 + 7);
int n, a[MAXN], p[MAXN];
int cmp(int x, int y) { return a[x] < a[y]; }
int main() {
  while (cin >> n) {
    for (int i = 1; i <= n; i++) {
      cin >> a[i];
      p[i] = i;
    }
    sort(p + 1, p + n + 1, cmp);
    if (n == 1) {
      cout << -1 << endl;
      continue;
    }
    long long fi = a[p[1]], se = 0;
    for (int i = 2; i <= n; i++) se += a[p[i]];
    if (fi == se) {
      cout << -1 << endl;
    } else {
      cout << 1 << endl;
      cout << p[1] << endl;
    }
  }
  return 0;
}
