#include <bits/stdc++.h>
using namespace std;

int main() {
	int n;
	long long m;
	cin >> n >> m;
	vector<long long> A(n);
	for (int i = 0; i < n; i++)
		cin >> A[i];
	sort(A.begin(), A.end());
	vector<bool> B(n, false);
	B[0] = true;
	vector<long long> C;
	for (int i = 1; i < n; i++) {
		if (A[i] * (n - 1) < m) {
			cout << -1 << endl;
			return 0;
		}
		if (!B[i]) {
			long long k = A[i] * 2;
			for (int j = i + 1; j < n; j++) {
				if (A[j] > k) {
					cout << -1 << endl;
					return 0;
				}
				if (A[j] == k) {
					B[j] = true;
					k += A[i];
				}
			}
			C.push_back(A[i]);
		}
	}
	cout << C.size() << endl;
	for (int i = 0; i < C.size(); i++) {
		if (i)
			cout << ' ';
		cout << C[i];
	}
	cout << endl;
	return 0;
}