#include <iostream>
using namespace std;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))

int n[10010];
int main(){
    int N;
    cin >> N; N++;
    REP(i,N) cin >> n[i];

    for(int i = N-1; i >= 3; i--) n[i-2] += n[i], n[i] = 0;

    int i = 2;
    while(n[i] == 0) i--;

    cout << i << endl;
    REP(j,i) cout << n[j] << " "; cout << n[i] << endl;
}