#include <iostream>
using namespace std;
int max(int n, int a[]) {
	int max = a[1];
	for (int i = 0; i < n; i++) {
		if (a[i] > max) max = a[i];
	}
	return max;
}

int min(int n, int a[]) {
	int min = a[1];
	for (int i = 0; i < n; i++) {
		if (a[i] < min) min = a[i];
	}
	return min;
}

int main() {
	int N, M, MAX, MIN;
	int sum = 0;
	int a[100];
	int b[1001];
	int c[100];
	int p = 1;
	cin >> N;
	for (int j = 0; j < 100; j++) {
		a[j] = 0;
		b[j] = 0;
	}
	for (int i = 0; i < N; i++) {
		cin >> a[i];
		b[a[i]] = 1;
	}
	MAX = max(N, a);
	MIN = min(N, a);
	for (int k = MIN; k <= MAX; k++) {
		if (b[k] == 1) {
			sum++;
			c[p] = k;
			p++;
		}
	}
	M = sum;
	cout << M << endl;
	for (int m = 1; m <= M; m++) {
		cout << c[m] << " ";
	}
	return 0;
}