import java.util.*;
public class Main{
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int a = scan.nextInt();
		int b = scan.nextInt();
		int[] f = new int[b];
		for(int i=0;i<a;i++){
			int c = scan.nextInt();
			for(int l=0;l<c;l++){
				int d = scan.nextInt();
				f[d-1]++;
			}
		}
		int ans=0;
		Arrays.sort(f);
		for(int i=b-1;i>=0;i--){
			if(f[i]!=a){break;}else{ans++;}
		}
		System.out.println(ans);
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz