#include <fstream>
#include <algorithm>
#include <queue>
using namespace std;

ifstream fin("lupu.in");
ofstream fout("lupu.out");

struct oaie
{
    int dist, pufosenie;
    bool operator<(const oaie &other) const
    {
        return pufosenie < other.pufosenie;
    }
};

priority_queue<oaie> oile;
oaie oi[100005];

bool cond_sort_oi(oaie a, oaie b)
{
    return a.dist < b.dist;
}

int main()
{
    long long raspuns = 0;
    int n, x, l, contor = 0;
    fin >> n >> x >> l;
    for (int i = 0; i < n; i++)
        fin >> oi[i].dist >> oi[i].pufosenie;
    sort(oi, oi + n, cond_sort_oi);
    for (int i = 0; i <= x / l; i++)
    {
        while (contor < n && oi[contor].dist <= l * i)
            oile.push(oi[contor++]);
        if (!oile.empty())
        {
            raspuns += oile.top().pufosenie;
            oile.pop();
        }
    }
    fout << raspuns << "\n";
    return 0;
}