package yukicoder;

import java.util.*;

public class Q451 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long[] b = new long[n + 1];
		long[] a = new long[n + 2];
		long Max = 1_000_000_000_000_000_000L;
		for (int i = 1; i <= n; ++i) {
			b[i] = sc.nextLong();
			if ((i + 1) % 2 == 0)
				a[i + 1] += b[i];
			else
				a[i + 1] -= b[i];
		}
		a[1] = 1;
		for (int i = 2; i <= n + 1; ++i) {
			if (i % 2 == 0) {
				a[i] -= a[i - 1];
			} else {
				a[i] += a[i - 1];
			}
			if (a[i] > 2 * Max || a[i] < -Max) {
				System.out.println(-1);
				return;
			}
		}

		long oddMax = -Long.MAX_VALUE;
		long oddMin = Long.MAX_VALUE;
		long evenMax = -Long.MAX_VALUE;
		long evenMin = Long.MAX_VALUE;
		for (int i = 1; i <= n + 1; ++i) {
			if (i % 2 == 1) {
				oddMax = Math.max(oddMax, a[i]);
				oddMin = Math.min(oddMin, a[i]);
			} else {
				evenMax = Math.max(evenMax, a[i]);
				evenMin = Math.min(evenMin, a[i]);
			}
		}

		ArrayDeque<Long> que = new ArrayDeque<>();
		// oddにどれだけ加算するか
		que.add(Max - oddMax);
		que.add(-Max + evenMax);
		que.add(1 - oddMin);
		que.add(-1 + evenMin);
		while (!que.isEmpty()) {
			long add = que.poll();
			if (oddMax + add <= Max && oddMax + add > 0 && evenMax - add <= Max && evenMax - add > 0 && oddMin + add > 0
					&& oddMin + add <= Max && evenMin - add > 0 && evenMin - add <= Max) {
				System.out.println(n + 1);
				for (int i = 1; i <= n + 1; ++i) {
					if (i % 2 == 1) {
						System.out.println(a[i] + add);
					} else {
						System.out.println(a[i] - add);
					}
				}

				for (int i = 1; i <= n; ++i) {
					if (i % 2 == 0) {
						assert b[i] == a[i] - a[i + 1];
					} else {
						assert b[i] == a[i] - a[i + 1];
					}
				}
				return;
			}
		}
		System.out.println(-1);

	}

	static void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}