#include <cstdio>
#include <vector>
using namespace std;
int main() {
    int jack, jill,input;
    while (scanf("%d%d",&jack, &jill) == 2) {
        if (jack==0 && jill==0) break;
        vector <int> jacks;
        vector <int> jills;
        int i,j,mx,cnt=0;
        for (i=0;i<jack;i++) {
            scanf("%d",&input);
            jacks.push_back(input);
        }
        for (i=0;i<jill;i++) {
            scanf("%d",&input);
            jills.push_back(input);
        }
        if (jack > jill) {
            for (i=0;i<jack;i++) {
                for (j=0;(j<jill) && (jacks[i] >= jills[j]);j++) {
                    if (jacks[i] == jills[j]) {
                        cnt++;
                        break;
                    }
                }
            }
        }
        else {
            for (i=0;i<jill;i++) {
                for (j=0;(j<jack) && (jills[i] >= jacks[j]);j++) {
                    if (jills[i] == jacks[j]) {
                        cnt++;
                        break;
                    }
                }
            }
        }

        printf("%d\n",cnt);
    }

    return 0;
}