#include <bits/stdc++.h>
using namespace std;
int n,dp[1001][1001],i,j,a[1001],b[1001];
int main() {
	cin>>n;
	for(i = 1;i <= n;i++){
		cin>>a[i];
	}
	
	for(i = 1;i <= n;i++){
		cin>>b[i];
	}
	
	/*
	  计算a序列取i个元素，b序列取j个元素下的最长公共子序列长度
	*/ 
	for(i = 1;i <= n;i++){
		for(j = 1;j <= n;j++){
			if(a[i] == b[j]){
				dp[i][j] = dp[i-1][j-1] + 1;
			}else{
				dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
			}
		}
	}
	
	cout<<dp[n][n];
	return 0;
}
/**************************************************************
	Problem: 1821
	User: admin
	Language: C++
	Result: Accepted
	Time:44 ms
	Memory:5996 kb
****************************************************************/