/*
IN THE NAME OF GOD
*/
#include <bits/stdc++.h>
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef long double ld;
#define F first
#define S second
#define Mp make_pair
#define pb push_back
#define pf push_front
#define size(x) ((ll)x.size())
#define all(x) (x).begin(),(x).end()
#define kill(x) cout << x << '\n', exit(0);
#define fuck(x) cout << "(" << #x << " , " << x << ")" << endl
#define endl '\n'
const int N = 3e5+23, lg = 18;
ll Mod = 1e9+7; //998244353;
inline ll MOD(ll a, ll mod=Mod) {a%=mod; (a<0)&&(a+=mod); return a;}
inline ll poww(ll a, ll b, ll mod=Mod) {
ll ans = 1;
a=MOD(a, mod);
while (b) {
if (b & 1) ans = MOD(ans*a, mod);
b >>= 1;
a = MOD(a*a, mod);
}
return ans;
}
int t, n, pos[N], a[N], b[N], pd[5005], mx[5005][5005], dp[5005][5005];
vector<int> comp;
int main () {
ios_base::sync_with_stdio(false), cin.tie(0);
cin>>n;
if (n > 5000) kill(0);
for(int i=1; i<=n; i++) cin>>a[i], comp.pb(a[i]);
for(int i=1; i<=n; i++) cin>>b[i];
sort(all(comp)); comp.resize(unique(all(comp)) - comp.begin());
for(int i=1; i<=n; i++) {
int ptr = lower_bound(all(comp), a[i]) - comp.begin() + 1;
a[i] = ptr;
mx[i][i] = a[i];
ptr = lower_bound(all(comp), b[i]) - comp.begin();
if(ptr>=0 && ptr<size(comp) && comp[ptr]==b[i]) b[i] = ptr+1;
else b[i] = 0;
}
for(int l=1; l<=n; l++) for(int r=l+1; r<=n; r++) mx[l][r] = max(mx[l][r-1], mx[r][r]);
for(int i=1; i<=n; i++) dp[1][i] = (b[i]==a[i] && mx[1][i]==a[i]);
for(int i=1; i<=n; i++) {
int maxi = 0;
for(int j=1; j<=n; j++) {
maxi = max(maxi, dp[i-1][j]);
if(mx[min(i,j)][max(i,j)] == a[j]) {
dp[i][j] = maxi + (b[i] == a[j]);
}
}
}
int ans = 0;
for(int i=1; i<=n; i++) ans = max(ans, dp[n][i]);
cout<<ans<<endl;
return 0;
}
