为什么会全部wa呢

using namespace std;
#define ll long long
#define N 1001

int main() {
	int n;
	int arr[N];
	int ct = 0;
	int arr2[N];
	cin >> n;
	for (int i = 0; i < n; i++) {
		int x;
		cin >> x;
		arr[x] = 1;
	}
	for (int i = 0; i <=1000; i++) {
		if (arr[i] > 0)
		{
			arr[ct++] = i;
			
		}
	}
	cout << ct << endl;
	for (int i = 0; i < ct; i++) {
		cout << arr[i]<<" ";
	}
	return 0;
}