#include "bits/stdc++.h"
#define REP(i,n,N) for(ll i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
typedef long long ll;
using namespace std;
const ll inf=1e18;

int D;
int a[10010];
int main(){
    cin>>D;
    REP(i,0,D+1){
        cin>>a[i];
    }
    RREP(i,3,D+1){
        a[i-2]+=a[i];
        a[i]=0;
    }
    int ansD=0;
    if(a[2]) ansD=2;
    else if(a[1]) ansD=1;
    p(ansD);
    REP(i,0,ansD+1){
        if(i) cout<<" "<<a[i];
        else cout<<a[i];
    }
    cout<<endl;
    return 0;
}