#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define rep(a,b) for(int a = 0; a < (b); ++a)
#define all(t) t.begin(), t.end()
#define pb push_back
#define fi first
#define se second
const int N = 5005, INF = 2e9+54321;
const ll INF_L = (ll)2e18+54321;
int n;
int A[N], B[N];
int dp[N];
void solve()
{
cin >> n;
rep(i,n) cin >> A[i];
rep(i,n) cin >> B[i];
rep(i,n)
{
if(i == 0) dp[i] = 0;
else dp[i] = dp[i-1];
int czy = 0, il = 0;
for(int j = i; j >= 0 and A[j] <= B[i]; --j)
{
if(A[j] == B[i]) czy = 1;
if(B[j] == B[i]) ++il;
int cost = il;
if(j-1 >= 0) cost += dp[j-1];
if(czy) dp[i] = max(dp[i],cost);
}
//cout << "I: " << i << " DP: " << dp[i] << '\n';
}
cout << dp[n-1] << '\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int T = 1;
//cin >> T;
while(T--) solve();
return 0;
}
