#include <bits/stdc++.h>
#include<algorithm>
using namespace std;

struct city{
        int latitude;
        int longitude;
        int height;
        int points;
    city(int lat, int lon, int ht, int p):latitude(lat),longitude(lon),
        height(ht),points(p){}
        
};

struct less_than_key
{
    inline bool operator() (const city& struct1, const city& struct2)
    {
        return (struct1.height < struct2.height);
    }
};

int maxSubArraySum(const vector<int>& a)
{
    int max_so_far = INT_MIN, max_ending_here = 0;
 
    for (int i = 0; i < a.size(); i++)
    {
        max_ending_here = max_ending_here + a[i];
        if (max_so_far < max_ending_here)
            max_so_far = max_ending_here;
 
        if (max_ending_here < 0)
            max_ending_here = 0;
    }
    return max_so_far;
}

int main(){
    int n;
    int x;
    int y;
    vector<city> cities;
    cin >> n >> x >> y;
    for(int a0 = 0; a0 < n; a0++){
        int latitude;
        int longitude;
        int height;
        int points;
        cin >> latitude >> longitude >> height >> points;
        cities.push_back(city(latitude, longitude, height, points) );
    }
    sort(begin(cities),end(cities),less_than_key() );
    vector<int> pointVec;
    for(auto iter: cities){
        //cerr <<  "height: " << iter.height << endl;
        pointVec.push_back(iter.points);
    }
    cout << maxSubArraySum(pointVec);
    return 0;
}