Persian Party

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

int main(){

    long n, v=0;
        cin>> n;

    vector <long> a(n);
    vector <long> d(n);

        for(long i=0; i<n; i++){
            cin>> a[i];
            cin>> d[i];
        }
    sort(a.begin(), a.end());
    sort(d.begin(), d.end());

    for(long p=0, i=0, j=0; i<n;){
        if(a[i]<d[j]){
            p++;
            v+=p-1;
            i++;
        }
        else{
            p--;
            j++;
        }
    }
    cout<<(v+n)*2;
}