#include <iostream>

 #include <stdio.h>

 using namespace std;

 int a[];

 int b[];

 int n;

 bool search(int x)

 {

 int l = , r = n-;

 int mid = (l+r)/;

 while(l <= r)

 {

   if (a[mid] < x){

     l = mid+;

     mid = (l+r) / ;

   }

   else if (a[mid] > x)

   {

     r = mid-;

     mid = (l+r)/;

    }

   else return true;

 }

 return false;

 }

 int main()

 {

     freopen("in.txt", "r", stdin);

   int m, ans = ;

   while(~scanf("%d%d", &n, &m))

   {

       ans = ;

        if ( m==  && n == ) break;

        for (int i = ; i < n; i++)

        scanf("%d", &a[i]);

        int tmp;

        for (int i = ; i < m; i++)

        {

            scanf("%d", &tmp);

             if (search(tmp))

              ans++;

         }

          printf("%d\n", ans);

     }

 return ;

 }