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

#define MAXX 100000



typedef struct DATE {
	unsigned long int a;
	unsigned long int b;
	} date;
date in[MAXX];
date out[MAXX];


void merge(int low, int high, int mid) {
	int i, j, k;
	unsigned long int c[500],d[500];
	i=low;
	j=mid+1;
	k=low;
	while((i<=mid)&&(j<=high)) { // sortez dupa in.a
		//if(a[i]<a[j]) 
		if (in[i].a > in[j].a) {
			c[k]=in[i].a;
			d[k]=in[i].b;
			k++;
			i++;
		}
		else {
			c[k]=in[j].a;
			d[k]=in[j].b;
			k++;
			j++;
		}
	}
	while(i <= mid) {
		c[k]=in[i].a;
		d[k]=in[i].b;
		k++;
		i++;
	}
	while(j<=high){
		c[k]=in[j].a;
		d[k]=in[j].b;
		k++;
		j++;
	}
	for(i=low;i<k;i++) {
		in[i].a=c[i];
		in[i].b=d[i];
	}
} 



void mergesort( int low, int high) {
	int mid;
	if(low<high) {
		mid=(low+high)/2;
		mergesort(low,mid);
		mergesort(mid+1,high);
		merge(low,high,mid);
	}
}

int main () {
	
	FILE *f,*g;
	f=fopen("gutui.in","r");
	g=fopen("gutui.out","w");
	//unsigned long 
	unsigned long int n,h,u; // n:numar de gutui h: inamtimea max u:cu cat se ridica crengile
	fscanf (f, "%lu %lu %lu",&n,&h,&u);
	char c[MAXX];
	fgets(c,MAXX,f); // sa ajung pe urm linie
	int i,j;
	
	unsigned long int gmax=0; // greutatea maxima
	
	for (i=0;i<n;i++) {
		fscanf (f, "%lu %lu",&in[i].a,&in[i].b);	
		fgets(c,MAXX,f);// \n
	}
	printf ("\n hi \n"); // print la citire
	for (i=0;i<n;i++)
		printf ("%lu ",in[i].a);
		
	printf ("\n ui \n");
	for (i=0;i<n;i++)
		printf ("%lu ",in[i].b);
	//sortare
	
	mergesort(0,n);
	printf ("\n sortat hi \n"); // print la citire
	for (i=0;i<n;i++)
		printf ("%lu ",in[i].a);
		
	printf ("\n sortat ui \n");
	for (i=0;i<n;i++)
		printf ("%lu ",in[i].b);
		
	
	//deci asadar si prin urmare
	//acum iau fiecare elem din hi vad daca pot sa il adaug la structura
	//daca pot il adaug : daca nu p ot vad ce element as putea inlocui a i structura sa fie optima
	//in hi : inaltime ui : greutate ; h: cat am disponibil ; u : cat o sa scad
	//haux[MAXX], uaux[MAXX],gmaxi[MAXX]; e 
	int k = 0; //contor pt a numara cate elem voi avea in haux[MAXX], uaux[MAXX]; 
	for (i = 0; i < n;i ++ )
		if (in[i].a <= h) {
			out[k].a = in[i].a;
			out[k].a = in[i].b;
			gmax += in[i].b; //adaug la greutate
			 
			h -= u ; //scad inaltimea
			k++; //cresc nr de elem
		}
		else {
		//aici e prob : ma uit in cele adaugate deja si vad pe care il pot inlocui
			for (j=0;j<k;j++)
				if ( in[i].b > out[j].b ) { //compar greutatea cu h mai mari 
					//printf (" %lu %lu %lu",gmax,ui[i],uaux[j]);
					
					gmax =gmax + in[i].b - out[j].b;
					out[j].a = out[i].a;
					 
					out[j].b = out[i].b;
					
					//printf ("gmax %lu pentru hi %lu \n",gmax,hi[i]);
				}
		}
/*	printf ("\n haux \n");	
	for (i=0;i<k;i++)
		printf ("%lu ",haux[i]);
		
	printf ("\n uaux \n");
	for (i=0;i<k;i++)
		printf ("%lu ",uaux[i]);
	printf ("\ngreutate maxima la la la %lu \n" , gmax);	
		*/
	fprintf(g, "%lu",gmax);
		
		
	return 0;
}