import java.util.Scanner;

public class N40 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int d=sc.nextInt();
		int[] a=new int[d+1];
		int dd=-1;
		int[] b=new int[3];
		for(int i=0;i<=d;i++){
			a[i]+=sc.nextInt();
			if(i<d-2){
				a[i+2]+=a[i];
				a[i]=0;
			}
		}
		int ind=0;
		for(int i=0;i<=d;i++){
			if(dd==-1&&a[i]!=0){
				dd=d-i;
				ind=i;
			}
		}
		if(dd==-1){
			System.out.println(0+"\n"+0);
		}
		else{
			System.out.println(dd);
			for(int i=ind;i<=d;i++){
				System.out.print(a[i]+" ");
			}
		}
	}
}