#include<stdio.h>

#define MAX 10000

unsigned int alt[MAX];
unsigned int kg[MAX];
int N;

unsigned int U, H;

int tot[MAX];  //gutui culese
int nrc;     //nr gutui culese

int minim(){
         int i;
         int min=0;
         for(i=1;i<nrc;i++){
                if(kg[tot[i]]<kg[tot[min]])
                min=i;
                }
         return min;
         }
                                            


int main(){
   
   FILE *f;

f=fopen("gutui.in","r");
fscanf(f,"%d",&N);
fscanf(f,"%d",&H);
fscanf(f,"%d",&U);

int i,j;
unsigned int aux;

for(i=0;i<N;i++){
                fscanf(f,"%d",&alt[i]);
                fscanf(f,"%d",&kg[i]);
                              
                } 
    
    
for(i=0;i<N-1;i++)
                for(j=i+1;j<N;j++)
                {
                                if(alt[i]<alt[j])
                                {
                                                 aux=alt[i];
                                                 alt[i]=alt[j];
                                                 alt[j]=aux;
                                                 aux=kg[i];
                                                 kg[i]=kg[j];
                                                 kg[j]=aux;
                                                 
                                }
                }
unsigned int hmax=H;
nrc=0;
for(i=0;i<N;i++){
                 if(alt[i]<=hmax){
                                 tot[nrc++]=i;
                                 hmax-=U;
                                 }
                                 else
                                 {
                                     j=minim();  //elementul j din tot[] are greutatea minima
                                     if(kg[i]>kg[j])
                                                    tot[j]=i;
                                 }
                 }
 unsigned int total=0;
 
 for(i=0;i<nrc;i++){
                    total += kg[tot[i]];
                    }
                    
  
 FILE* g;
  g=fopen("gutui.out","w");
  fprintf(g,"%d",total);
  fclose(f);
  fclose(g);
 return 0;
}