import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int D = sc.nextInt();
        int [] a = new int [D+1];
        for(int i=0; i<=D; i++){
            a[i] = sc.nextInt();
        }
        for(int i=D; i>=3; i--){
            a[i-2]+=a[i];
            a[i]=0;
        }
        int c=0;
        for(int i=D-3; i>=0; i--){
            if(a[i]!=0){
                c=i;
                break;
            }
        }
        System.out.println(c);
        for(int i=0; i<=c; i++){
            System.out.print(a[i]);
            if(i!=c){System.out.print(" ");}
        }
        System.out.println();
    }
}