import java.awt.geom.Point2D;
import java.io.*;
import java.math.*;
import java.util.*;
import java.util.Map.*;







class Main {

	public static void main(String[] args) {	
		//FastScanner sc = new FastScanner();
		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 > 2; i--) {
			int tmp = a[i];
			a[i] = 0;
			a[i-2] -= -tmp;
		}
		int[] DD = new int[10];
		int tmp = 0;
		IN:for(int i = D; i >= 0; i--) {
			if(a[i] != 0) {
				tmp = i;
				for(int j = i; j >= 0; j--) {
					DD[j] = a[j];
					
				}
				break IN;
			}
		}
		System.out.println(tmp);
		System.out.print(DD[0]);
		for(int i = 1; i <= tmp; i++) System.out.print(" " + DD[i]);
		System.out.println();
	}


	
	static class FastScanner {
	    private final InputStream in = System.in;
	    private final byte[] buffer = new byte[1024];
	    private int ptr = 0;
	    private int buflen = 0;
	    private boolean hasNextByte() {
	        if (ptr < buflen) {
	            return true;
	        }else{
	            ptr = 0;
	            try {
	                buflen = in.read(buffer);
	            } catch (IOException e) {
	                e.printStackTrace();
	            }
	            if (buflen <= 0) {
	                return false;
	            }
	        }
	        return true;
	    }
	    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
	    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
	    private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;}
	    public boolean hasNext() { skipUnprintable(); return hasNextByte();}
	    public String next() {
	        if (!hasNext()) throw new NoSuchElementException();
	        StringBuilder sb = new StringBuilder();
	        int b = readByte();
	        while(isPrintableChar(b)) {
	            sb.appendCodePoint(b);
	            b = readByte();
	        }
	        return sb.toString();
	    }
	    public long nextLong() {
	        if (!hasNext()) throw new NoSuchElementException();
	        long n = 0;
	        boolean minus = false;
	        int b = readByte();
	        if (b == '-') {
	            minus = true;
	            b = readByte();
	        }
	        if (b < '0' || '9' < b) {
	            throw new NumberFormatException();
	        }
	        while(true){
	            if ('0' <= b && b <= '9') {
	                n *= 10;
	                n += b - '0';
	            }else if(b == -1 || !isPrintableChar(b)){
	                return minus ? -n : n;
	            }else{
	                throw new NumberFormatException();
	            }
	            b = readByte();
	        }
	    }
	    public int nextInt() {
	        if (!hasNext()) throw new NoSuchElementException();
	        int n = 0;
	        boolean minus = false;
	        int b = readByte();
	        if (b == '-') {
	            minus = true;
	            b = readByte();
	        }
	        if (b < '0' || '9' < b) {
	            throw new NumberFormatException();
	        }
	        while(true){
	            if ('0' <= b && b <= '9') {
	                n *= 10;
	                n += b - '0';
	            }else if(b == -1 || !isPrintableChar(b)){
	                return minus ? -n : n;
	            }else{
	                throw new NumberFormatException();
	            }
	            b = readByte();
	        }
	    }
	}
}