#include <cstdio>

const int NMAX = 524288;

int N, sol;
long long V[NMAX];
int pi[NMAX];

void read() {
	FILE *fin = fopen("reguli.in", "rt");
	long long last, current;
	char buf[16];
	int i, j;

	fscanf(fin, " %d", &N);

	fscanf(fin, " %lld", &last);
	--N;

	for (i = 0; i < N; ++i) {
		fscanf(fin, " %s", buf);

		for (current = 0, j = 0; buf[j]; ++j)
			current = current * 10 + (buf[j] - '0');

		V[i] = current - last;
		last = current;
	}

	fclose(fin);
}

void chimp() {
	int i, j;

	for (j = 0, i = 2; i <= N; ++i) {

		while (j > 0 && V[j] != V[i - 1]) j = pi[j];

		if (V[j] == V[i - 1]) ++j;

		pi[i] = j;
	}

	sol = N - pi[N];
}

void write() {
	FILE *fout = fopen("reguli.out", "wt");
	int i;

	fprintf(fout, "%d\n", sol);
	for (i = 0; i < sol; ++i)
		fprintf(fout, "%lld\n", V[i]);

	fclose(fout);
}

int main() {

	read();

	chimp();

	write();

	return 0;
}