#include <bits/stdc++.h>
using namespace std;
const int N = 1e4 + 10;
const int INF = 0x3f3f3f3f;
int n;
int a[N],b[N];
int dp[N][N];
int main(){
    cin >> n;
    for(int i = 1;i <= n;i++){
    	cin >> a[i];
	}
    for(int i = 1;i <= n;i++){
    	cin >> b[i];
	}
    for(int i = 1;i <= n;i++){
        int sum = 1;
        for(int j = 1;j <= n;j++){
            dp[i][j] = dp[i - 1][j];  
            if(a[i] == b[j]){
                dp[i][j] = max(dp[i][j],sum);
            }
            if(a[i] > b[j]){
                sum = max(sum,dp[i][j] + 1);
			}  
        }
    }
    int nmax = -INF;
    for(int i = 1;i <= n;i++){
    	nmax = max(nmax,dp[n][i]);
	}
    cout << nmax;
}