#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define all(x) (x).begin(), (x).end()
bool be;
constexpr int N = 55;
int n, k, a[N];
inline bool check(int l, int r)
{
	int len = r - l + 1, p = r + 1;
	for (int o = 1; o < k; ++o) {
		if (p + len - 1 > n) return 0;
		for (int i = l; i <= r; ++i) {
			if (a[i] != a[p + i - l]) {
				return 0;
			}
		}
		p += len;
	}
	return 1;
}
bool en;
int main() {
	cerr << (&be - &en) / 1024.0 / 1024 << " MB\n--------------------------------" << endl;
#ifdef IAKIOI
	freopen("in.in", "r", stdin);
//	freopen("out.out", "w", stdout);
#endif
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> n >> k;
	for (int i = 1; i <= n; ++i) {
		cin >> a[i];
	}
	for (int l = 1; l <= n; ++l) {
		for (int r = l; r <= n; ++r) {
			if (check(l, r)) {
				cout << r - l + 1 << '\n';
				for (int k = l; k <= r; ++k) cout << a[k] << ' ';
				return 0;
			}
		}
	}
	cout << "-1\n";
	return 0;
}