#include <bits/stdc++.h>
using namespace std;
	
typedef long long ll;
typedef unsigned long long ull;
typedef long double db;
	
#define MOD 1000000007
#define mini 18446744073709551615
#define ff first
#define ss second
#define pb push_back
#define vii vector<int>
#define pii pair<int,int>
#define vpii vector<pii>
#define mii map <int,int>
#define all(v) (v.begin(),v.end())

bool findPartition(vii arr, int n)
{
    int sum = 0;
    int i, j;
    for (i = 0; i < n; i++)
        sum += arr[i];
 
    if (sum % 2 != 0)
        return false;
    bool part[sum / 2 + 1][n + 1];
    for (i = 0; i <= n; i++)
        part[0][i] = true;
    for (i = 1; i <= sum / 2; i++)
        part[i][0] = false;
    for (i = 1; i <= sum / 2; i++) {
        for (j = 1; j <= n; j++) {
            part[i][j] = part[i][j - 1];
            if (i >= arr[j - 1])
                part[i][j] = part[i][j]
                             || part[i - arr[j - 1]][j - 1];
        }
    }
    return part[sum / 2][n];
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int T=1;
	// cin>>T;
	while(T--)
	{
		int n,me=2001,mitr=0,f=0;
		cin>>n;
		vii a(n);
		for(int i=0;i<n;i++)
		{
			cin>>a[i];
			if(a[i]<me)
			{
				me=a[i];
				mitr=i;
			}
		}
		if(findPartition(a,n))
		{
			for(int i=0;i<n;i++)
			{
				int tem=a[i];
				a[i]=0;
				if(!findPartition(a,n))
				{
					f=1;
					mitr=i;
					break;
				}
				a[i]=tem;
			}
		}
		if(f)
			cout<<"1\n"<<mitr+1<<"\n";
		else cout<<"0\n";
	}
	return 0;
}