#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
using loop = int;
template<class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i,a,n) for(loop (i)=(a);(i)<(n);++(i))
#define eFOR(i,a,n) for(loop (i)=(a);(i)<=(n);++(i))
#define rFOR(i,a,n) for(loop (i)=(n)-1;(i)>=(a);--(i))
#define erFOR(i,a,n) for(loop (i)=(n);(i)>=(a);--(i))
#define each(i, a) for(auto &i : a)
#define SORT(i) sort((i).begin(),(i).end())
#define rSORT(i,a) sort((i).begin(),(i).end(),(a))
#define all(i) (i).begin(),(i).end()
#define out(y,x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define line cout << "------------------------\n" 
#define ENDL(i,n) ((i) == (n) - 1 ? "\n" : " ")
#define stop system("pause") //comment out this on AOJ.
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr ld pi = 3.1415926535897932;
template<class T>inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T>inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; }return false; }
inline void init() { cin.tie(nullptr); cout.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); }
template<class T>inline istream& operator>>(istream& is, vector<T>& v) { for (auto& elemnt : v)is >> elemnt; return is; }
template<class T, class U>inline istream& operator>>(istream& is, pair<T, U>& p) { is >> p.first >> p.second; return is; }
template<class T>inline vector<T> vec(size_t a) { return vector<T>(a); }
template<class T>inline vector<T> defvec(T def, size_t a) { return vector<T>(a, def); }
template<class T, class... Ts>inline auto vec(size_t a, Ts... ts) { return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...)); }
template<class T, class... Ts>inline auto defvec(T def, size_t a, Ts... ts) { return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...)); }

int n;
vector<vector<tuple<int, int, int>>> g;
vector<bool> used;
bool dfs(int now) {
    used[now] = true;
    if (now == n * 2 + 1)return true;
    each(next, g[now]) {
        int to, cap, rev; tie(to, cap, rev) = next;
        if (used[to] || cap == 0)continue;
        if (dfs(to)) {
            --get<1>(next);
            ++get<1>(g[to][rev]);
            return true;
        }
    }
    return false;
}

int main() {
    init();

    cin >> n;
    VI a(n), b(n), c(n), d(n);
    FOR(i, 0, n)cin >> a[i] >> b[i];
    FOR(i, 0, n)cin >> c[i] >> d[i];

    g.resize(n * 2 + 2);
    FOR(i, 0, n) {
        g[n * 2].emplace_back(i, 1, g[i].size());
        g[i].emplace_back(n * 2, 0, g[n * 2].size() - 1);
        g[n + i].emplace_back(n * 2 + 1, 1, g[n * 2 + 1].size());
        g[n * 2 + 1].emplace_back(n + i, 0, g[n + i].size() - 1);
    }
    FOR(i, 0, n)FOR(j, 0, n) {
        if (a[i] < c[j] && b[i] < d[j]) {
            g[i].emplace_back(n + j, 1, g[n + j].size());
            g[n + j].emplace_back(i, 0, g[i].size() - 1);
        }
    }

    for (int ans = 0; true; ++ans) {
        used.assign(n * 2 + 2, false);
        if (!dfs(n * 2)) {
            cout << ans << "\n";
            break;
        }
    }
}

Measured memory_bytes: 384