//
// Created by zacharias on 2026-04-17.
//

#include <iostream>

int main() {
    int n;
    int m;


    while (scanf("%d %d", &n, &m) == 2 && n != 0 && m != 0) {
        int jack[n];
        int jill[m];

        for (int i = 0; i < n; i++) {
            scanf("%d", &jack[i]);
        }
        for (int i = 0; i < m; i++) {
            scanf("%d", &jill[i]);
        }

        int i = 0;
        int j = 0;
        int total = 0;

        while (i < n && j < m) {
            if (jack[i] == jill[j]) {
                total++;
                i++;
                j++;
            }
            else if (jack[i] < jill[j]) {
                i++;
            }
            else {
                j++;
            }
        }
        printf("%d\n", total);
    }
}