#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

ifstream f("pikachu.in");
ofstream g("pikachu.out");

int main() {
    int N, K, X, L;
    f >> N >> K >> X >> L;

    vector<vector<int>> heights_grouped(2 * N + 1);
    for (int i = 0; i < N; ++i) {
        int D, H;
        f >> D >> H;
        heights_grouped[D - X + N].push_back(H); //grupam inaltimile in functie de distanta fata de Pikachu
    }

    int total_sum = 0;
    for (auto& group : heights_grouped) {
        if (group.empty()) continue;
        sort(group.begin(), group.end(), greater<int>());
        int group_sum = 0;
        for (int i = 0; i < min(K, (int)group.size()); ++i) {
        }
        total_sum += group_sum;
    }

    g << total_sum << endl;

    return 0;
}