#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;
const int maxn = 100010;
int C[maxn];
int n;
inline int read() {
	int x = 0, f = 1; char ch = getchar();
	while (ch < '0' || ch > '9') {if (ch == '-') f = -1; ch = getchar();}
	while (ch >= '0' && ch <= '9') {x = x * 10 + ch - 48; ch = getchar();}
	return x * f;
}
int lowbit(int x) {
    return x & (-x);
}
void update(int x, int v) {
    for (int i = x; i <= n; i += lowbit(i)) {
        C[i] = max(C[i], v);
    }
}
int getmax(int x) {
    int res = 0;
    for (int i = x; i > 0; i -= lowbit(i)) {
        res = max(res, C[i]);
    }
    return res;
}
int p1[maxn], p2[maxn];
vector<int> pos[maxn];
int dp[maxn];
int main() {
    n = read();
    n *= 5;
    for (int i = 1; i <= n; i++) {
        p1[i] = read();
    }
    for (int i = 1; i <= n; i++) {
        p2[i] = read();
        pos[p2[i]].push_back(i);
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 4; j >= 0; j--) {
            int temp = max(temp, getmax(pos[p1[i]][j] - 1) + 1);
            update(pos[p1[i]][j], temp);
            dp[i] = max(dp[i], temp);
        }
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        ans = max(ans, dp[i]);
    }
    printf("%d\n", ans);
    return 0;
}