#include <iostream>
#include <cstring>
#include <queue>
using namespace std;
const int M = 20, N = 1 << M;
int n, m, k;
int a[100];
short dis[N];
int main() {
	cin >> n >> m >> k;
	for (int i = 0; i < n; i++)
		for (int i = 0; i < k; i++) {
			int t;
			cin >> t;
			a[i] |= 1 << (t - 1);
		}
	memset(dis, -1, sizeof(dis));
	dis[0] = 0;
	queue<int> q;
	q.push(0);
	while (!q.empty()) {
		int u = q.front();
		q.pop();
		for (int i = 0; i < n; i++) {
			int v = u | a[i];
			if (dis[v] == -1) {
				q.push(v);
				dis[v] = dis[u] + 1;
			}
		}
	}
	cout << dis[(1 << m) - 1];
	return 0;
}