#include<iostream>
#include<algorithm>

using namespace std ;

const int N = 3010;

int n,a[N],b[N],f[N][N];

int main()
{
    scanf("%d",&n);
    for(int i = 1;i<=n; ++i)scanf("%d",&a[i]);
    for(int i = 1;i<=n; ++i)scanf("%d",&b[i]);


    for (int i = 1; i <= n; i ++ )
    {
        int maxv = 1;
        for (int j = 1; j <= n; j ++ )
        {
            f[i][j] = f[i - 1][j];
            if(a[i]==b[j]) f[i][j] = max(maxv,f[i][j]);
            if(a[i]>b[j]) maxv = max(maxv,f[i-1][j] + 1);
        }
    }

    int res = 0;
    for(int i =1 ;i<= n ;++ i)res = max(f[n][i],res);
    cout << res ;

    return 0;
}