#include <fstream>
#include <queue>
#include <algorithm>

using namespace std;

struct oaia
{
    int dist, lana;
};

bool cmp(oaia x, oaia y)
{
    return (x.dist > y.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(), cmp);
    long long total_lana = 0;
    priority_queue <int, vector <int>, greater <int>> selectate;
    int timp_c = 0;
    for (int i = 0; i < n; i++)
    {
        if (v[i].dist + timp_c * indepartare <= dist_max)
        {
            selectate.push(v[i].lana);
            total_lana += v[i].lana;
            timp_c++;
        }
        else
        {
            if (!selectate.empty() && v[i].lana > selectate.top())
            {
                ///preferam oaia i
                total_lana += v[i].lana - selectate.top();
                selectate.pop();
                selectate.push(v[i].lana);
            }
        }
    }
    out << total_lana << "\n";
    in.close();
    out.close();
    return 0;
}