import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int[] A = new int[n];
        int[] B = new int[m];
        for(int i = 0;i < n;i++){
            A[i]=sc.nextInt();
        }
        for(int i = 0;i < m; i++) {
            B[i]=sc.nextInt();
        }
        int count = 0;
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < n; ++j) {
                if (A[i] == B[j]){
                    count++;
                }
            }
        }
        System.out.println(count);
    }
}