#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define pii pair<ll, ll>
#define fi first
#define se second
const ll N = 4e5 + 5, inf = 1e18, mod = 1e9 + 7, block = 320, lim = 1 << 16;
int n;
pii a[N], b[N];
vector <int> comp;
vector <int> color[N];
struct ST {
    vector <int> st, lz;
    ST (int _n) {
        st.assign(4 * (_n + 1), 0);
        lz.assign(4 * (_n + 1), 0);
    }
    void lazy(int i, int l, int r) {
        if (lz[i] != 0) {
            if (l < r) {
                st[2 * i] += lz[i];
                st[2 * i + 1] += lz[i];
                lz[2 * i] += lz[i];
                lz[2 * i + 1] += lz[i];
            }
            lz[i] = 0;
        }
    }
    void update(int i, int l, int r, int u, int v, int val) {
        if (u > r || v < l) return;
        if (u <= l && r <= v) {
            st[i] += val;
            lz[i] += val;
            return;
        }
        lazy(i, l, r);
        int mid = (l + r) / 2;
        update(2 * i, l, mid, u, v, val);
        update(2 * i + 1, mid + 1, r, u, v, val);
        st[i] = min(st[2 * i], st[2 * i + 1]);
    }
    int get(int i, int l, int r, int u, int v) {
        lazy(i, l, r);
        if (u > r || v < l) return inf;
        if (u <= l && r <= v) return st[i];
        int mid = (l + r) / 2;
        return min(get(2 * i, l, mid, u, v), get(2 * i + 1, mid + 1, r, u, v));
    }
} st(N);
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    if (fopen(".inp", "r")) {
        freopen(".inp", "r", stdin);
        freopen(".out", "w", stdout);
    }
    cin >> n;
    for (int i = n; i >= 1; i--) cin >> a[i].fi >> a[i].se;
    for (int i = n; i >= 1; i--) cin >> b[i].fi >> b[i].se;
    for (int i = 1; i <= n; i++) {
        comp.push_back(a[i].se);
        comp.push_back(b[i].se);
    }
    sort(comp.begin(), comp.end());
    comp.erase(unique(comp.begin(), comp.end()), comp.end());
    for (int i = 1; i <= n; i++) {
        a[i].se = lower_bound(comp.begin(), comp.end(), a[i].se) - comp.begin() + 1;
        b[i].se = lower_bound(comp.begin(), comp.end(), b[i].se) - comp.begin() + 1;
    }
    int sz = comp.size();
    int ptr = 1, res = 0;
    for (int i = 1; i <= n; i++) {
        while(ptr <= n && a[ptr].se <= b[i].se) {
            st.update(1, 1, sz, a[ptr].se, sz, 1);
            color[a[ptr].fi].push_back(a[ptr].se);
            ptr++;
        }
        if (color[b[i].fi].size() > 0 && st.get(1, 1, sz, color[b[i].fi].back(), sz) > 0) {
            st.update(1, 1, sz, color[b[i].fi].back(), sz, -1);
            color[b[i].fi].pop_back();
        }
        else {
            st.update(1, 1, sz, b[i].se, sz, -1);
            res++;
        }
    }
    cout << res;
    return 0;
}
Compilation message (stderr)
worst_reporter2.cpp: In function 'int main()':
worst_reporter2.cpp:60:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
worst_reporter2.cpp:61:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 |         freopen(".out", "w", stdout);
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