code c++ ạ

#include <bits/stdc++.h>
#define ll long long
#define ios ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#pragma GCC optimize("O3","unroll-loops")
#pragma GCC optimize("Ofast")
using namespace std;
int main() {
    ios
    ll n;
    cin>>n;
    vector<pair<ll,ll>>a;
    for(int i=0;i<n;i++)
    {
        ll p,d;
        cin>>p>>d;
        a.push_back(make_pair(p,1));
        a.push_back(make_pair(d,-1));
    }
    sort(a.begin(),a.end());
    ll m=0;
    ll l=0;
    for(const auto&c:a)
    {
        l+=c.second;
        m=max(m,l);
    }
    cout<<m ;
    return 0;
}