#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1e9;
int MOD = 1000000007;
main(){
    int D,A[10001];
    cin >> D;
    for(int i = 0;i <= D;i++)cin >> A[i];
    for(int i = D;i >= 3;i--){
        A[i-2] += A[i];
        A[i] = 0;
    }
    D = 2;
    for(int i = 2;i > 0;i--){
        if(!A[i])D--;
        else break;
    }
    cout << D << endl;
    for(int i = 0;i <= D;i++)printf("%d%c",A[i],i==D?'\n':' ');
}