/*
 * File:   Problema2.c
 * Author: Bosilca Adrian 325CC
 *
 */
#include <stdio.h>
#include <stdlib.h>

typedef struct gutuie{
    int h;
    int g;
}gutuie;

int comp(const void* a, const void* b) {
    gutuie *c = (gutuie*)a;
    gutuie *d = (gutuie*)b;
    if ((c->g) == (d->g))
        return (d->h - c->h);
    return ( d->g - c->g );
}

int main() {
    FILE* f = fopen("gutui.in", "r");
    int n, h, u, i, k = 0, s = 0, hh;
    gutuie v[100000];
    int niv[100000] = {0};

    fscanf(f, "%d %d %d", &n, &h, &u);            //citirea datelor de intrare
    for (i = 0 ; i < n ; i++)
        fscanf(f, "%d %d", &v[i].h, &v[i].g);
    fclose(f);

    qsort(v, n, sizeof(gutuie), comp);

    for (i = 0 ; i < n ; i++) {
        hh = (h-v[i].h)/u;
        if (hh < k) {
            v[i].h = h+1;
        } else {
            if (hh == k) {
                niv[k] = 1;
                k++;
            } else {
                while (niv[hh] != 0 && hh > k)
                    hh--;
                if (hh >= k)
                    niv[hh] = 1;
            }
        }
        while (niv[k] != 0)
            k++;
    }

    for (i = 0 ; i < n; i++) {
        if (v[i].h <= h) {
            s += v[i].g;
        }
    }

    f = fopen("gutui.out", "w");
    fprintf(f, "%d", s);
    fclose(f);

    return 0;
}