#include <bits/stdc++.h>
using namespace std;
const int iINF = 1e9;
const int maxN = 5023;
int N, M, A[maxN], B[maxN];
vector<int> compress;
int dp[maxN][maxN], mx[maxN][maxN], pf[maxN][maxN];
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
cin >> N;
for (int i = 1; i <= N; i++) {
cin >> A[i];
compress.push_back(A[i]);
}
for (int i = 1; i <= N; i++) {
cin >> B[i];
compress.push_back(B[i]);
}
sort(compress.begin(), compress.end());
compress.erase(unique(compress.begin(), compress.end()), compress.end());
M = compress.size();
for (int i = 1; i <= N; i++) {
A[i] = lower_bound(compress.begin(), compress.end(), A[i]) - compress.begin() + 1;
B[i] = lower_bound(compress.begin(), compress.end(), B[i]) - compress.begin() + 1;
}
for (int l = 1; l <= N; l++) {
mx[l][l] = A[l];
for (int r = l+1; r <= N; r++) {
mx[l][r] = max(mx[l][r-1], A[r]);
mx[r][l] = mx[l][r];
}
}
for (int i = 1; i <= N; i++) {
for (int val = 1; val <= N; val++) {
pf[i][val] = -iINF;
}
}
pf[0][0] = 0;
for (int i = 1; i <= N; i++) {
for (int val = 1; val <= N; val++) {
if (mx[val][i] == A[val]) {
dp[i][val] = pf[i-1][val] + (B[i] == A[val]);
// cout << "dp[" << i << "][" << val << "] = " << dp[i][val] << '\n';
} else {
dp[i][val] = -iINF;
}
pf[i][val] = max(pf[i][val-1], dp[i][val]);
}
}
int ans = pf[N][N];
cout << ans << '\n';
}
