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

int A[100100];

int main(){
	int n,k;
	cin >> n;
	for(int i=0;i<n+1;i++) cin >> A[i];
	
	for(int i=n;i>=3;i--){
		A[i-2]+=A[i];
	}
	
	k=2;
	while(k&&A[k]==0) k--;
	
	cout << k << endl;
	for(int i=0;i<k+1;i++){
		cout << A[i];
		cout << (i==k?"\n":" ");
	}
	return 0;
}