/**
 *	author:	 fractal
 *	timus: 	 288481RF
 *	created: 04/21/21 21:23
**/

#include <bits/stdc++.h>
using namespace std;

#define F first
#define S second 
#define mp make_pair
#define pb push_back
#define pf push_front
#define ppb pop_back
#define ppf pop_front
#define speed ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#define sz(x) (int)x.size()
#define len(x) (int)strlen(x)
#define all(x) x.begin(), x.end()
#define debug cerr << "OK\n";
#define ub upper_bound
#define lb lower_bound 
#define nl printf("\n");
#define clbuff fflush(stdin);

mt19937 bruh(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rofl(chrono::steady_clock::now().time_since_epoch().count());
 
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
typedef set<int> si;
typedef set<ll> sll;
typedef set<pii> spii;
typedef set<pll> spll;
typedef multiset <int> msi;
typedef multiset <ll> msll;
typedef map <int, int> mi;
typedef map <ll, ll> mll;
 
const int N = 1e6 + 2;
const int M = 2e5;
const int mod = 0;
const int inf = 2e9 + 3;
const ll INF = 1e18;
const ld pi2 = 2.0 * 3.141592;
const ld pi = 3.141592;
const ld eps = 1e-12;

const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, -1, 1};

void files(string s = "main") {
	#ifndef PC
		freopen((s + ".in").c_str(), "r", stdin);
		freopen((s + ".out").c_str(), "w", stdout);
	#endif
}

int add(int a, int b) {
	if (a + b < 0) return a + b + mod;
	if (a + b >= mod) return a + b - mod;
	return a + b;		
}

int mul(int a, int b) {
	return a * 1LL * b % mod;
}

int binpow(int a, int n) {
	int ret = 1;
	while (n) {
		if (n & 1) ret = mul(ret, a);
		a = mul(a, a);
		n >>= 1;
	}
	return ret;
}

int n, a[N], s;
bitset<200001> dp;

int main() {
	speed;
	int T = 1;
	while (T--) {
		cin >> n;
		//~ n = 100;
		s = 0;
		//~ cerr << T << '\n';
		for (int i = 1; i <= n; ++i) {
			cin >> a[i];
			//~ a[i] = (bruh() % 500 + 1) * 4;
			s += a[i];
		}
		dp.reset();
		dp[0] = 1;
		bool ans = 0;
		for (int i = 1; i <= n; ++i) {
			dp |= (dp << a[i]);
		}
		if (s % 2 == 1) {
			cout << 0 << '\n';
			return 0;
			//~ ans = 1;
		}
		if (dp[s / 2] == 0) {
			cout << 0 << '\n';
			return 0;
			//~ ans = 1;
		}
		for (int i = 1; i <= n; ++i) {
			if ((s - a[i]) % 2 == 1) {
				cout << 1 << "\n" << i << '\n';
				return 0;
			}
		}
		for (int i = 1; i <= n; ++i) {
			dp.reset();
			dp[0] = 1;
			for (int j = 1; j <= n; ++j) {
				if (i == j)
					continue;
				dp |= (dp << a[j]);
			}
			if (dp[(s - a[i]) / 2] == 0) {
				cout << 1 << "\n" << i << '\n';
				return 0;
				//~ ans = 1;
			}
		}
	}
}
