/*
 * File:   Problema2.c
 * Author: Bosilca Adrian 325CC
 *
 */

#include <stdio.h>
#include <stdlib.h>

int u;

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

void afisare(gutuie v[], int n) {
    int i;
    for (i = 0 ; i < n ; i++) {
        printf("%d %d %d\n", v[i].g, v[i].h, i*10);
    }
    printf("\n");
}

int comp1(const void* a, const void* b) {
    gutuie *c = (gutuie*)a;
    gutuie *d = (gutuie*)b;
    if ((c->h-1/u) == (d->h-1/u))
        return (d->g - c->g);
    return ( d->h - c->h );
}

int comp2(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, i, j, dif = 0, k = 0, s1 = 0, s2 = 0;
    gutuie v[100000], aux;

    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), comp1);

    dif = 0;
    for (i = 0 ; i < n; i++) {
        if (v[i].h+dif <= h) {
            s1 += v[i].g;
            dif += u;
        }
    }

    qsort(v, n, sizeof(gutuie), comp2);

    dif = 0;
    for (i = 0 ; i < n; i++) {
        if (v[i].h+dif <= h) {
            s2 += v[i].g;
            dif += u;
        }
    }

    f = fopen("gutui.out", "w");
    if (s1 <= s2)
        fprintf(f, "%d", s2);
    else
        fprintf(f, "%d", s1);
    fclose(f);

    return 0;
}