#include<stdio.h>
#include<stdlib.h>
#define N 100000
FILE *fin, *fout;
unsigned long int n,h,u;
unsigned long int hg[N], g[N];
int alegere(int pas)
{
	unsigned long int maxh=0,maxg=0;
	int i,ales=0;
	for(i=0;i<n;i++)
		if(maxh < hg[i] && (hg[i] + (pas * u) <=h)) 
			maxh=hg[i];
	for(i=0;i<n;i++)
		if(maxh == hg[i] && maxg< g[i])
		{
			maxg=g[i];
			ales=i;
		}
	


	return ales;
}
int haccesibil(int pas)
{
	int i;
	for(i=0;i<n;i++)
		if(hg[i] + (pas * u) <= h) 	return 1;
	return 0;
}



int main(void) {
	fin = fopen("gutui.in", "r");
	fout = fopen("gutui.out", "w");
	int i;
	fscanf(fin, "%lu %lu %lu", &n, &h, &u);
	printf("%lu %lu %lu\n \n",n,h,u);
	for (i = 0; i < n; i++) {
		fscanf(fin, "%lu %lu", &hg[i], &g[i]);
		printf("%lu %lu \n", hg[i], g[i]);
	}
	printf("\n \n");
	int ales,pas=0;
	unsigned long int suma=0;
	while(haccesibil(pas))
	{
		ales=alegere(pas);
		pas++;
		suma=suma+g[ales];
		hg[ales]=h+u;
		
	}
	fprintf(fout,"%lu\n",suma);		
	fclose(fin);
	fclose(fout);
	return 0;
}