/*
https://www.infoarena.ro/problema/lupu
*/
#include <fstream>
#include <queue>
#include <vector>
#include <algorithm>

using namespace std;

struct oaia
{
    int dist, lana;
};

bool operator < (oaia o1, oaia o2)
{
    return (o1.dist > o2.dist);
}

int main()
{
    ifstream in("lupu.in");
    ofstream out("lupu.out");
    int n, dist_max, indepartare;
    in >> n >> dist_max >> indepartare;
    vector <oaia> v(n);
    for (int i = 0; i < n; i++)
    {
        in >> v[i].dist >> v[i].lana;
    }
    sort(v.begin(), v.end());
    int timp = 0;
    long long total_lana = 0;
    priority_queue <int, vector <int>, greater <int>> h_sel;
    for (int i = 0; i < n; i++)
    {
        if (v[i].dist + timp * indepartare <= dist_max)
        {
            total_lana += v[i].lana;
            h_sel.push(v[i].lana);
            timp++;
        }
        else if (!h_sel.empty() && v[i].lana > h_sel.top())
        {
            total_lana += (v[i].lana - h_sel.top());
            h_sel.pop();
            h_sel.push(v[i].lana);
        }
    }
    in.close();
    out << total_lana << "\n";
    out.close();
    return 0;
}