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

typedef struct furcte{
    uint32_t  inaltime;
    uint32_t  greutate;
    uint32_t  ef;
}fructe;

uint32_t sort_by_inaltime( const void *a, const void *b ){
    fructe *ia = ( fructe * )a;
    fructe *ib = ( fructe * )b;

    return (uint32_t)( ib->inaltime - ia->inaltime );
	/*  returns negative if b > a
            and positive if a > b. */
}

uint32_t sort_by_greutate( const void *a, const void *b ){
    fructe *ia = ( fructe * )a;
    fructe *ib = ( fructe * )b;

    return (uint32_t)( ib->greutate - ia->greutate );
        /*  returns negative if b > a
            and positive if a > b. */
}

int main(){
    FILE * f = fopen( "gutui.in", "r" );
    FILE * g = fopen( "gutui.out", "w" );
    uint32_t N,H,U,i, masa = 0;
    fructe x[100000];

     if ( f == NULL )                                       /* eroare la deschiderea fisierului */
         perror ("Error opening file");
    else{
         fscanf(f, "%u%u%u", &N, &H, &U  );                 /* nr de gutui, inaltimea maxima, cu cat creste distanta */

         for ( i = 0; i < N; i++){                           /* citirea elementelor structurii => greutatea si inaltimea unde se afla o gutuie */
             fscanf(f, "%u%u", &x[i].inaltime, &x[i].greutate );
             x[i].ef = x[i].greutate / x[i].inaltime;
         }


         qsort(x, N, sizeof(fructe), sort_by_inaltime);     /* sortez descrescator dupa inaltime */
         /* qsort(x, N, sizeof(fructe), sort_by_greutate);

         for ( i = 0; i < N; i++)
             printf("%u %u\n", x[i].inaltime, x[i].greutate); */
         i = 0;
         int k = 0;
         while ( i < N ){
             if ( (x[i].inaltime + k*U) <= H ){
                 masa += x[i].greutate;
                 k++;
             }
             i++;
         }

         fprintf(g, "%u", masa);

    }

    fclose(f);
    fclose(g);
    return 0;
}