package src;

import java.util.*;
class B{
	static Scanner s = new Scanner(System.in);
	public static void main(String[] args) {
		long[] out = new long[s.nextInt()+1];
		long buf=1;
		out[0]=buf;
		for(int i=1;i<out.length;++i) {
			if(i%2==0) {
				buf=(out[i]=buf-Long.parseLong(s.next()));
			}else {
				buf=(out[i]=Long.parseLong(s.next())-buf);
			}
		}

		long b1=Long.MAX_VALUE;
		long b2=Long.MAX_VALUE;
		for(int i=0;i<out.length;i++) {
			if(i%3==0)
				b1=Math.min(b1, out[i]);
			else
				b2=Math.min(b2, out[i]);
		}

		if(buf<=0){
			if(b1+b2-1<=0){
				System.out.println(-1);
				return;
			}
			long b = -b2+1;
			for(int i=0;i<out.length;i++) {
				if(i%3==0)
					out[i]+=b;
				else
					out[i]-=b;
			}
		}

		System.out.println(out.length);
		for(int i=0;i<out.length;i++)
			System.out.println(out[i]);
	}
}