#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)


int main() {
    ll D;
    cin>>D;
    vll A(D+1);
    rep(i,D+1)cin>>A[i];
    reverse(all(A));
    rep(i,D-2){
        A[i+2]+=A[i];
        A[i]=0;
    }
    
    reverse(all(A));

    if(A[2]!=0){
        cout<<2<<endl;
        cout<<A[0]<<" "<<A[1]<<" "<<A[2]<<endl;

    }
    else if(A[1]!=0){
        cout<<1<<endl;
        cout<<A[0]<<" "<<A[1]<<endl;
    }
    else cout<<0<<endl<<A[0]<<endl;
    
}