#include <fstream>
#include <algorithm>

using namespace std;

const int NMAX = 100000;

pair<long long, long long> v[1 + NMAX];

bool comp(const pair<long long, long long>& a, const pair<long long, long long>& b)
{
    return a.first > b.first;
}

int main()
{
    ifstream in("lupu.in");
    ofstream out("lupu.out");

    long long n, x, l;
    in >> n >> x >> l;

    for (int i = 1; i <= n; i++)
    {
        in >> v[i].second >> v[i].first;
    }

    sort(v + 1, v + 1 + n, comp);

    long long sol = 0;

    int nrOiLuate = 0;

    for (int i = 1; i <= n; i++)
    {
        if (x >= v[i].second + nrOiLuate * l)
        {
            sol += v[i].first;
            nrOiLuate++;
        }
    }

    out << sol << '\n';

    return 0;
}