#include <fstream>
#include <algorithm>
#include <vector>
#include <queue>
#define DIM 100002

using namespace std;

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

long long n;

long long s, x, l, val, maxim, curent, scop, cnt;

struct oaie
{
    long long d, lana;
}oi[DIM];

bool cmp(oaie a, oaie b)
{
    if(a.d == b.d)
        return a.lana > b.lana;
    return a.d < b.d;
}

priority_queue <long long> h;

int main()
{
    f>>n>>x>>l;

    for(int i = 1; i <= n; ++ i)
    {
        f>>oi[i].d>>oi[i].lana;
        if(l != 0)
            val = (x - oi[i].d) / l + 1;
        else
            val = oi[i].d;
        if(maxim < val)
            maxim = val;
        if(val > 0)
        {
            oi[i].d = val;
        }
    }

    sort(oi + 1, oi + n + 1, cmp);

    cnt = n;

    for(long long i = maxim; i >= 1; -- i)
    {
        while(oi[cnt].d == i)
        {
            h.push(oi[cnt].lana);
            -- cnt;
        }
        if(!h.empty())
        {
            s += h.top();
            h.pop();
        }

    }

    g<<s;

    return 0;
}