#include<stdio.h>
int a[5000000] = { 0 }, b[5000000] = { 0 };
int main()
{
	int n, m;
	scanf("%d %d", &n, &m);
	for (int i = 0; i < n; i++)
		scanf("%d", &a[i]);
	for (int i = 0; i < m; i++)
		scanf("%d", &b[i]);
	for(int i=0;i<n;i++)
		for (int j = 0; j < m; j++)
		{
			if (a[i] == b[j])
			{
				a[i] = 0;
				break;
			}
		}
	int cnt = 0;
	for (int i = 1; i < n - 1; i++)
	{
		if (a[i] == 0&&a[i+1]!=0)
			cnt++;
	}
	printf("%d", ++cnt);
	return 0;
}