#include<bits/stdc++.h>
#define int long long
#define INF INT_MAX
using namespace std;
const int maxn=(1<<20)+5;
int n,m,k;
int dp[maxn],val[maxn];
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	cin>>n>>m>>k;
	memset(dp,0x3f3f3f3f,sizeof(dp));
	for(int i=1;i<=n;i++){
		int p=0;
		for(int j=1;j<=k;j++){
			int x;
			cin>>x;
			p|=(1<<(x-1));
		}
		dp[p]=1;
		val[i]=p;
	}
	for(int i=0;i<(1<<m);i++){
		for(int j=1;j<=n;j++){
			dp[i|val[j]]=min(dp[i|val[j]],dp[i]+1);
		}
	}
	if(dp[(1<<m)-1]!=0x3f3f3f3f) cout<<dp[(1<<m)-1]<<endl;
	else cout<<-1<<endl;
	return 0;
}