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

typedef struct {long i; long g;} Gutui;
long n, h, u, i;

long compare (const void * b, const void * a){
    long r;
    if ((h-(*(Gutui*)b).i)/u!=(h-(*(Gutui*)a).i)/u)
        r=((Gutui*)a)->i - (*(Gutui*)b).i;
    else
        r=((Gutui*)a)->g - (*(Gutui*)b).g;
    if (r>0) return 1;
        else if (r<0) return -1;
    return 0;
}

int main(){        
   
    Gutui *g;
    long *c, picks=1, j;    
    FILE *f,*f2;
    f=fopen("gutui.in","rt");
    f2=fopen("gutui.out","wt");
    
    fscanf(f,"%li",&n);
    fscanf(f,"%li",&h);
    fscanf(f,"%li",&u);
    g = (Gutui*)malloc(n*sizeof(Gutui));   
    for (i=0;i<n;i++){
        fscanf(f,"%li",&g[i].i);
        fscanf(f,"%li",&g[i].g);
    }
    if (n<h/u)
        c=(long*)malloc(n*sizeof(long));
    else
        c=(long*)malloc((h/u+1)*sizeof(long)); 
    
    qsort (g, n, sizeof(Gutui), compare);
 
    c[0]=g[0].g;//culeg gutuia cea mai grea de pe nivelul cel mai inalt
    for (i=1;i<n;i++)
        if ((h-g[i].i)/u>=picks){//daca pot culege adaug greutatea la vectorul de solutii
            if (c[picks-1]<g[i].g){
                for (j=picks-1;j>=0;j--)
                    if (c[j]<g[i].g)
                        c[j+1]=c[j];
                    else
                        break;
                j++;
                c[j]=g[i].g;
                picks++;
            }
            else
                c[picks++]=g[i].g;
        }
        else if ((h-g[i].i)/u>=picks-1){//daca am cules nr maxim de gutui pana la momentul respectiv
            if (c[picks-1]<g[i].g){//verific daca gutuia curenta e mai grea decat ce mai usoara gutuie din vectorul de solutii
                if (c[picks-2]<g[i].g){
                    for (j=picks-2;j>=0;j--)
                        if (c[j]<g[i].g)
                            c[j+1]=c[j];
                        else
                            break;
                    j++;
                    c[j]=g[i].g;
                }
                else
                    c[picks-1]=g[i].g;
            }
        }

    j=0;                  
    for (i=0;i<picks;i++)
        j+=c[i];
    fprintf(f2,"%li",j);

    return 0;
}