#include <bits/stdc++.h>
using namespace std;
typedef long long lli;
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);  
#define pb push_back 
#define int long long

int dp[201][20001];

int numSubseq(int n , vector<int>& a, int s , int pos1 = -2 , int pos2 = -2 )
{
	if( n == pos1 || n == pos2 ) 
		return numSubseq( n - 1 , a , s ) ;
    if(n==-1)
    {
        if(s==0) return 1;
        return 0;
    }
    if(s<0) return 0;
    if(s==0) return 1;
    if(dp[n][s]!=-1) return dp[n][s];
    return dp[n][s] = numSubseq(n-1,a,s-a[n]) || numSubseq(n-1,a,s);
}

signed main()
{     
	memset(dp,-1,sizeof(dp));
	int n , sum = 0 ;
	cin >> n ; 
	vector<int> a(n) ;
	for( auto &it : a )
		cin >> it , sum += it ; 

	if( sum % 2 ) 
	{
		cout << 0 ;
		return 0 ;
	} 
	if( !numSubseq( n -1 , a , sum / 2 ) )
	{
		cout << 0;
		return 0 ;
	}

	for( int i = 0 ; i< n ; i++ ) 
	{
		int target = sum - a[i] ;
		if( target % 2 ) 
		{
			cout << 1 << endl; 
			cout << i + 1; 
			return 0 ; 
		} 
		if( !numSubseq(n-1,  a , target / 2 , i ) )
		{
			cout <<  1 << endl ;
			cout << i + 1 << endl ; 
			return 0 ;
		}
	}


	for( int i = 0 ; i < n; i++ )
	{
		for( int j = 0 ; j < n ; j++ )
		{
			if( i == j ) continue ;
			int target = sum - a[i] - a[j] ; 
			if( target % 2 ) 
			{
				cout << 2 << endl ;
				cout << i +1 << " " << j + 1 << endl ;
				return 0 ; 
			}
			if( !numSubseq(n-1, a , target / 2 , i , j ) ) 
			{
				cout << 2 << endl ;
				cout << i + 1 << ' ' << j + 1 <<endl ;
				return 0 ;
			}
		}
	}
} 