#include<stdio.h>
#include<list>
#include<stdlib.h>
using namespace std;
FILE* fin;
FILE* fout;

typedef struct gut{


    unsigned int greutate;
    unsigned int tmp;

}*gutui;
bool compare_desc(gut first,gut second)
{


  if (first.tmp <= second.tmp) return true;
  else return false;
}


int main(){

    unsigned int** mat;

   unsigned int h,u,a,g,maxim;

    fin=fopen("gutui.in","r");
    fout=fopen("gutui.out","w");
    int n,i,j,max;
    int t;

    list<gut> cos;
    list<gut>::iterator it;



    fscanf(fin,"%d %d %d\n",&n,&h,&u);
 gut *aux;

 if(h%u==0)
 {
     t=0;
 max=h/u;

 }else
 {max=h/u+1;
 t=1;
 }
    for(i=0;i<n;i++)
    {
     aux=(gut*)malloc(sizeof(struct gut));


        fscanf(fin,"%u %u\n",&a,&g);

        if(a+(max-t-(a/u))*u<=h)

        aux->tmp=max-t-(a/u-1);
        else
            aux->tmp=max-t-(a/u);

        //aux->inaltime=a;
        aux->greutate=g;
        cos.push_back(*aux);
       
        free(aux);

    }

    cos.sort(compare_desc);

   /* for (it=cos.begin(); it!=cos.end(); ++it)
        printf("%u %u\n",it->greutate,it->tmp);
*/




    mat=(unsigned int**)malloc(sizeof(unsigned int*)*2);
    it=cos.begin();







   
        mat[0]=(unsigned int*)calloc((max+1),sizeof(unsigned int));
        mat[1]=(unsigned int*)calloc((max+1),sizeof(unsigned int));

       
    //it=cos.begin();

    //printf("%d %d\n",1,it->greutate);





    printf("max=%d\n",max);

    it=cos.begin();
    for(i=1;i<=n;i++)
    {
        

  //  printf("i=%d tmp=%d\n",i,it->tmp);

   

/*for(j=0;j<=max;j++)
    printf("%d ",mat[0][j]);
    printf("\n");
 */
   for(j=1;j<=max;j++)
        {
       mat[0][j]=mat[1][j];
            
                

                if(j>(int)(it->tmp))
                {mat[1][j]=mat[1][it->tmp];

                }
                else
                {
                maxim=mat[0][j];


               // printf("%d %d\n",j,it->greutate);


                if(maxim<mat[0][j-1]+it->greutate)
                   maxim=mat[0][j-1]+it->greutate;

                mat[1][j]=maxim;

                }



        }

    /*for(j=0;j<=max;j++)
    printf("%d ",mat[1][j]);
    printf("\n\n");
    */
   if((int)it->tmp==max)
       break;
        ++it;
    }




   

 /*for(i=0;i<=n;i++)
    {
for(j=0;j<=max;j++)
    printf("%d ",mat[i][j]);
  printf("\n");
 }
*/
        printf("%u\n",mat[1][max]);
        
       fprintf(fout,"%u",mat[1][max]);


      /*  for(i=0;i<=n;i++)
        */
       free(mat[0]);
       free(mat[1]);
       
        free(mat);


        fclose(fin);
        fclose(fout);

    return 0;
}