#include <iostream>
#include <cstring>

using namespace std;

const int N = 105;
const int M = N * 2005;

int a[N];
int dp[M];

int main() {
	int n;
	cin >> n;
	int sum = 0;
	int mn = 3000;
	int tag = -1;
	int tt = -1;
	for (int i = 1; i <= n; i ++ ) {
		cin >> a[i];
		sum += a[i];
		if (a[i] & 1) tt = i;
		if (a[i] % 2 == 0 && a[i] < mn) {
			mn = a[i];
			tag = i;
		}
	}
	if (sum & 1) {
		cout << "0"; 
	} else {
		for (int i = 1; i <= n; i ++ ) {
			for (int j = sum; j >= a[i]; j --) {
				dp[j] = max(dp[j], dp[j - a[i]] + a[i]);
			}
		}
		if (dp[sum / 2] != sum / 2) {
			cout << "0";
		} else {
			cout << "1\n";
			if (tt != -1) cout << tt;
			else 
			for (int k = 1; k <= n; k ++ ) {
				memset(dp, 0, sizeof dp);
				for (int i = 1; i <= n; i ++ ) {
					if (i == k) continue;
					for (int j = sum - a[k]; j >= a[i]; j --) {
						dp[j] = max(dp[j], dp[j - a[i]] + a[i]);
					}
				}
				if (dp[(sum - a[k]) / 2] != (sum - a[k]) / 2) {
					cout << k;
					break;
				}
			}
		}
	}
	return 0;
}