#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const int LIM=5007;
int a[LIM], b[LIM], dp[LIM][LIM], ma[LIM][LIM];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int n;
cin >> n;
rep(i, n) cin >> a[i+1];
rep(i, n) cin >> b[i+1];
rep(i, n) {
for(int j=i; j<n; ++j) {
ma[i+1][j+1]=max(ma[i+1][j], a[j+1]);
}
}
rep(i, n) rep(j, n) {
dp[i+1][j+1]=max(dp[i+1][j], dp[i][j+1]);
if(a[i+1]==b[j+1] && ma[min(i+1, j+1)][max(i+1, j+1)]==a[i+1]) {
dp[i+1][j+1]=max(dp[i+1][j+1], dp[i+1][j]+1);
}
}
cout << dp[n][n] << '\n';
}
