#include <bits/stdc++.h>
using namespace std;
inline long long read() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (ch > '9' || ch < '0') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
int lis[15], tot, m = 0x3f3f3f3f, ans;
int main() {
  int n = read();
  for (int i = 0; i < n; i++) {
    lis[i] = read();
    tot += lis[i];
    if (m > lis[i]) {
      m = lis[i];
      ans = i;
    }
  }
  if (m * 2 == tot || m == tot)
    cout << -1 << endl;
  else
    cout << 1 << endl << ans + 1 << endl;
  return 0;
}
