#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int d;
    cin >> d;
    int a[d+1] = {};
    int b[d+1] = {};
    rep(i,d+1)cin >> a[i];
    drep(i,d+1){
        if(i < 3){
            break;
        }
        b[i-3] = a[i];
        a[i] -= b[i-3];
        a[i-2] -= -b[i-3];
    }

    int ans = 0;
    rep(i,d+1){
        if(i >= 3)break;
        if(a[i] != 0)ans = i;
    }
    cout << ans << endl;
    rep(i,ans+1)cout << a[i] << ' ';
    cout << endl;
    
    return 0;
}