#include<bits/stdc++.h>
#define lli long long int
#define all(x) x.begin(),x.end()
#define ff first
#define ss second
#define pb push_back
using namespace std;
vector<int> subsetSum(int arr[], int n, int maxSum)
{

    bool dp[maxSum + 1];
    memset(dp, false, sizeof dp);
    dp[arr[0]] = true;
    for (int i = 1; i < n; i++) {
        for (int j = maxSum + 1; j >= 1; j--) {
            if (arr[i] <= j) {
                if (arr[i] == j || dp[j] || dp[(j - arr[i])])
                    dp[j] = true;
 
                else
                    dp[j] = false;
            }
        }
    }
 
    // If dp [j] is true then print
    vector<int>ans;
    ans.push_back(0);
    for (int j = 0; j < maxSum + 1; j++) {
        if (dp[j] == true)
           ans.push_back(j);
    }
    return ans;
}
vector<int> subsetSum(int arr[], int n, int maxSum,int ii,int jj,int kk)
{

    bool dp[2*maxSum + 1];
    memset(dp, false, sizeof dp);
    int ll=1;
    if(ii!=0){dp[arr[0]] = true;}
    else if(n>3&&ii==0&&jj==1&&kk==2){
       dp[arr[3]] = true;ll=4;
    }
    else if(ii==0&&jj==1&&n>2){dp[arr[2]] = true;ll=3;}
    else if(ii==0&&n>0){
        dp[arr[1]] = true;ll=2;
      }
    for (int i = ll; i < n; i++) {
        if(i==ii||i==jj||i==kk){
            continue;
        }
        else{
        for (int j = maxSum + 1; j >= 1; j--) {
            if (arr[i] <= j) {
                if (arr[i] == j || dp[j] || dp[(j - arr[i])])
                    dp[j] = true;
 
                else
                    dp[j] = false;
            }
        }
        }
    }
 
    // If dp [j] is true then print
    vector<int>ans;
    ans.push_back(0);
    for (int j = 0; j < maxSum + 1; j++) {
        if (dp[j] == true)
           ans.push_back(j);
    }
    return ans;
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
	int n;
	cin >> n;
	int a[n];
	int sum=0;
	int c=0;
	int v=0;
	for(int i=0;i<n;i++){
		cin >> a[i];
		if(a[i]%2==1){
			c++;
			v=i;
		}
		sum+=a[i];
	}
	if(sum%2==1){
		cout<<"0\n";
	}
	else if(sum%2==0&&v>0){
		vector<int>vv;
       vv=subsetSum(a,n,sum);
       if((vv.size())%2==0){
           cout<<"0\n";
          // cout<<v[(v.size()+1)/2-1]<<" "<<sum<<"\n";
           return 0;
       }
    cout<<"1\n";
		cout<<v+1<<"\n";
	} 
    else{   vector<int>v;
       v=subsetSum(a,n,sum);
       if((v.size())%2==0){
           cout<<"0\n";
          // cout<<v[(v.size()+1)/2-1]<<" "<<sum<<"\n";
           return 0;
       }
       else{
           int rr=v[(v.size()+1)/2]-v[(v.size()+1)/2-1];
           for(int i=0;i<n;i++){
               if(a[i]==rr){
                   cout<<"1\n";
                   cout<<i+1<<"\n";
                   return 0;
               }
           }
          for(int i=0;i<n;i++){
              if(((sum-a[i])/2)%2==1){
                  cout<<"1\n";
                  cout<<i+1<<"\n";
                  return 0;
              }
              else{
                  auto it=lower_bound(all(v),((sum-a[i])/2)+a[i])-v.begin();
                  if(it==n){
                      cout<<"1\n";
                  cout<<i+1<<"\n";
                  return 0;
                  }
                  else if(v[it]!=((sum-a[i])/2)+a[i]){
                      cout<<"1\n";
                  cout<<i+1<<"\n";
                  return 0;
                  }
              }
          }
          for(int i=0;i<n;i++){
              for(int j=i+1;j<n;j++){
                if(((sum-(a[i]+a[j]))/2)%2==1){
                  cout<<"2\n";
                  cout<<i+1<<" "<<j+1<<"\n";
                  return 0;
              }
              }
          }
          for(int i=0;i<n;i++){
              for(int j=i+1;j<n;j++){
                for(int k=j+1;k<n;k++){if(((sum-(a[i]+a[j]+a[k]))/2)%2==1){
                  cout<<"3\n";
                  cout<<i+1<<" "<<j+1<<" "<<k+1<<"\n";
                  return 0;
              }
              }
              }
          }
          for(int i=0;i<n;i++){
              for(int j=i+1;j<n;j++){
                for(int k=j+1;k<n;k++){if(((sum-(a[i]+a[j]+a[k]))/2)%2==1){
                  cout<<"3\n";
                  cout<<i+1<<" "<<j+1<<" "<<k+1<<"\n";
                  return 0;
              }
              }
              }
          }
          for(int i=0;i<n;i++){
              for(int j=i+1;j<n;j++){
                for(int k=j+1;k<n;k++){
                if(((sum-(a[i]+a[j]+a[k]))/2)%2==1){
                  cout<<"3\n";
                  cout<<i+1<<" "<<j+1<<" "<<k+1<<"\n";
                  return 0;
              }
              }
              }
          }
    }
}
}