#include<stdio.h>
#include <algorithm>
#include <list>
#include <map>
using namespace std;
#define min(a,b)  (a < b)?(a):(b)
struct gutuie{
    int h,g;
};
unsigned int getLevel(gutuie Gutuie, int H, int U){
    if(H >= Gutuie.h)
        return (1+getLevel(Gutuie,H-U,U));
    return 0;
}
bool compare(const gutuie &g1, const gutuie &g2){
    return g1.g > g2.g;
}
map<unsigned int, list<gutuie> > Gutui;

bool countHeavier(unsigned int level,unsigned int nrNiv,unsigned int chosen){
    unsigned int i, counter;
    for(i = level+1;i<nrNiv+1;i++){
        counter = 0;
        list<gutuie>::iterator it;
        for(it = (Gutui[i]).begin(); it != (Gutui[i]).end(); it++)
            if((Gutui[level].front().g) < (*it).g)
                counter++;
        if(counter >= i-chosen+1)
            return true;
    }
    return false;
}

unsigned int GMAX(unsigned int nrNiv, unsigned int N){
    unsigned int i,chosen=0,gr = 0,numarGutui=0,impr=0;
    for(i=1;i<nrNiv+1;i++){
        if(Gutui[i].empty())
            impr++;
        else{
            if(Gutui[i].size() ==1)
                numarGutui++;
            else{
                if(impr>Gutui[i].size()-1){
                    numarGutui+=Gutui[i].size();
                    impr-=(Gutui[i].size()-1);
                }
                else{
                    numarGutui+=(impr+1);
                    impr = 0;
                }
            }
        }
    }
    for(i=1;i<nrNiv+1;i++){
        if(i<=chosen)
            i=chosen+1;
      //  printf("iteratia %i Mai sunt %i nivele\n",i,nrNiv-i);
        if(!Gutui[i].empty()){
      //      printf("Acum ar trebui sa fac ceva i-chosen: %i\n", (i-chosen) );
            if(!countHeavier(i,nrNiv,chosen)){
               gr += (Gutui[i].front().g);
      //         printf("Adaug asta la greutate:%i %i\n",Gutui[i].front().h,Gutui[i].front().g);
               Gutui[i].pop_front();
               chosen++;
               i--;
               N--;
               numarGutui--;
            }
        else
            N-=Gutui[i].size();
        }
    }
    return gr;
}

int main(){
    unsigned int N,H,U,nrNiv,i;
    gutuie Gutuie;
    FILE *f=fopen("gutui.in","r"), *g=fopen("gutui.out","w");
    fscanf(f,"%u %u %u\n",&N,&H,&U);
    nrNiv = H/U;
    
    for(i=0;i<N;i++){
        fscanf(f, "%u %u\n", &(Gutuie.h), &(Gutuie.g));
        Gutui[getLevel(Gutuie,H,U)].push_front(Gutuie);
    }
    for(i=1;i<1+nrNiv;i++){
    //fprintf(g, "\n%i.",i);
   // list<gutuie>::iterator it;
        Gutui[i].sort(compare);
    //    for(it = (Gutui[i]).begin(); it != (Gutui[i]).end(); it++)
     //       fprintf(g,"%i %i|", (*it).h, (*it).g);
    }
    fprintf(g,"%u", GMAX(nrNiv, N));
    //scanf("%i",&N);
    fclose(f);
    fclose(g);
    return 0;
}