#include<iostream>
using namespace std; 
int main(void)
{
	int n,m,a[21]={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},c=0;
	cin>> n >> m;
	for(int i=1;i<n;i++){int x;cin >> x;a[i]++;}
	for(int i=1;i<m;i++){int x;cin >> x;a[i]++;}
	for(int i=0;i<20;i++)if(a[i]==2){c++;/*cout<<i<<endl;*/} 
	cout<<c;
}