//去重函数
int REMOVE_DUPLICATE(int n,int array[]) {
	int i,j,k=n,m;
	for (i = 0; i < k; i++) {
		if (array[i] == -1)continue;
		for(j=i+1;j<k;j++)
			if (array[i] == array[j]) {	
				array[j] = -1;	
				counter++;
			}
	}
	return 0;
}

//排序函数
void SEQUENCE(int n, int array[]) {
	int min = 0;
	for (int i = 0; i < n; i++)
	{
		for (int j = i + 1; j < n; j++)
		{
			if (array[j] < array[i])
			{
				min = array[j];
				array[j] = array[i];
				array[i] = min;
			}
		}
	}
}

   	int n;
   	cin >> n;
   	int* arr = new int[n];
   	for (int i = 0; i < n; i++)cin >> arr[i];
   	SEQUENCE(n, arr);
   	REMOVE_DUPLICATE(n, arr);
   
   	cout << n-counter << endl;
   	for (int i = 0; i < n; i++) {
   		if (arr[i]!=-1) {
   			cout << arr[i] << " ";
   		}
   	}
   	return 0;