COMMON

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define maxn 1000030

int a[maxn]
int b[maxn];
int n, m, q = 0, emax = -1;

void input () {
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; ++i) {
        scanf("%d", &a[i]);
        if (emax < a[i])
            emax = a[i];
    }
    for (int i = 0; i < m; ++i) {
        scanf("%d", &b[i]);
        if (emax < b[i])
            emax = b[i];
    }
}

void output () {
    printf("%d\n", q);
}

void solve () {
    int * f = (int*) malloc(sizeof(int) * (emax+1));
    memset(f, 0, sizeof(int) * (emax+1));
    for (int i = 0; i < n; ++i) {
        f[a[i]] = 1;
    }
    for (int i = 0; i < m; ++i) {
        if (f[b[i]]) {
            ++q;
            f[b[i]] = 0;
        }
    }
}

int main () {
    input();
    solve();
    output();
    return 0;
}