#include <cstdio>
#include <cmath>

typedef long long   signed int LL;
typedef long long unsigned int LU;

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define inc( i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec( i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))

template<typename T> void swap(T & x, T & y) { T t = x; x = y; y = t; return; }
template<typename T> T abs(T x) { return (0 <= x ? x : -x); }
template<typename T> T max(T a, T b) { return (b <= a ? a : b); }
template<typename T> T min(T a, T b) { return (a <= b ? a : b); }
template<typename T> bool setmin(T & a, T b) { if(a <= b) { return false; } else { a = b; return true; } }
template<typename T> bool setmax(T & a, T b) { if(b <= a) { return false; } else { a = b; return true; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

int n;
LL b[100000];
const LL MAX = 1000000000000000000LL;

int main() {
	scanf("%d", &n);
	inc(i, n) { scanf("%lld", &b[i]); }
	
	bool flag = false;
	LL l = 0, r = b[0], m;
	while(r - l > 1) {
		m = (l + r) / 2;
		flag = true;
		int ii;
		LL mm = m;
		inc(i, n) {
			mm = (b[i] - mm) * (i % 2 == 0 ? 1 : -1);
			if(! inII(mm, 1, MAX)) { flag = false; ii = i; break; }
		}
		if(! flag) {
			if(mm < 1) {
				if(ii % 4 < 2) { r = m; } else { l = m; }
			} else {
				if(ii % 4 < 2) { l = m; } else { r = m; }
			}
		} else { break; }
	}
	
	if(! flag) { printf("-1\n"); return 0; }
	
	printf("%d\n", n + 1);
	inc(i, n + 1) {
		printf("%lld\n", m);
		m = (b[i] - m) * (i % 2 == 0 ? 1 : -1);
	}
	
	return 0;
}