题解

#include <iostream>
#include <vector>
using namespace std;

int main() {
int n;
cin >> n;

vector<int> a(n + 1), b(n + 1);
for (int i = 1; i <= n; ++i) {
    cin >> a[i];
}
for (int i = 1; i <= n; ++i) {
    cin >> b[i];
}

vector<int> f(n + 1, 0);

for (int i = 1; i <= n; ++i) {
    int max_val = 0;
    for (int j = 1; j <= n; ++j) {
        if (a[i] == b[j]) {
            f[j] = max(f[j], max_val + 1);
        }
        if (b[j] < a[i]) {
            max_val = max(max_val, f[j]);
        }
    }
}

int ans = 0;
for (int i = 1; i <= n; ++i) {
    ans = max(ans, f[i]);
}

cout << ans << endl;

return 0;

}