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

//----------------------DEBUGGER---------------------//

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}


#ifdef LOCAL
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

//----------------------------Debugger End--------------------------//

#define ll long long
#define pb push_back
#define pll pair<ll,ll>
#define M 1000000007

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #ifdef LOCAL
    freopen("in", "r", stdin);
    freopen("out", "w", stdout);
    #endif

    ll t=1,i,j,k,n,sum,ind=-1;
    char ch;
    string s;
    bool ok;

    //cin>>t;

    while(t--)
    {
       cin>>n;
       vector<ll>v(n);
       //map<ll,ll>mp;
       sum=0; 
       for(i=0;i<n;i++)
       {
           cin>>v[i];
           sum+=v[i];
           if(v[i]%2==1) ind=i+1;
       }

       if(sum%2==1) cout<<0<<endl;
       else 
       {
         vector<ll>dp(sum+1,0);
         dp[0]=1;   
         for(i=0;i<n;i++)
         {
             for(j=sum;j>=0;j--)
             {
                 if(dp[j]>0) dp[j+v[i]]=1;
             }
             debug(dp);
         }

         if(dp[sum/2]==1)
         {
             cout<<1<<endl;
             if(ind!=-1) cout<<ind<<endl;
             else 
             {
                 for(i=0;i<n;i++)
                 {
                     if(dp[(sum-v[i])/2]==0)
                     {
                         cout<<i+1<<endl;
                         break;
                     }
                 }
             }
         }
         else cout<<0<<endl;
       }
    }

}

