#include <cstdio>

#define FOR(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define REV(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define INC0(i, n) FOR(i, 0, n)
#define INC1(i, n) FOR(i, 1, (n) + 1)
#define DEC0(i, n) REV(i, 0, n)
#define DEC1(i, n) REV(i, 1, (n) + 1)

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


int d, k[10001];
int a, b, c, x, y;

int main() {
	scanf("%d", &d);
	INC0(i, d + 1) { scanf("%d", &k[i]); }
	
	c = k[0];
	INC0(i, d + 1) {
		x += k[i];
		y += k[i] * (i % 2 == 0 ? 1 : -1);
	}
	
	if(x - c == c - y) {
		if(x - c == 0) {
			printf("0\n%d\n", c);
		} else {
			printf("1\n%d %d\n", c, x - c);
		}
	} else {
		b = (x - y) / 2;
		a = x - b - c;
		printf("2\n%d %d %d\n", c, b, a);
	}
	
	return 0;
}