#include <stdio.h>
#include <stdlib.h>
#include "include/heap.h"

#define infile "gutui.in"
#define outfile "gutui.out"

int NMAX = 100000;
int N, H, U;

typedef struct{
	int height;
	int weight;
} fruit;

int compare_h_fruit(void* A, void* B, void* context)
{
	fruit *a = A;
	fruit *b = B;

	if (a->height < b->height)
		return -1;
	if (a->height > b->height)
		return 1;	
	if (a->weight < b->weight)
		return -1;
	if (a->weight > b->weight)
		return 1;
		
	return 0;
}
int compare_w_fruit(void* A, void* B, void* context)
{
	fruit *a = A;
	fruit *b = B;
	
	if (a->weight < b->weight)
		return 1;
	if (a->weight > b->weight)
		return -1;
	if (a->height < b->height)
		return -1;
	if (a->height > b->height)
		return 1;
		
	return 0;
}

int sum(fruit *fr)
{
	int i, s = 0;
	for (i = 0; i < N; i++)
		s += fr[i].weight;
		
	return s;
}

int solve(fruit* fruits)
{
	if (U == 0)
		return sum(fruits);
	
	/* Create a heap and add all values from fruits in it */
	heap_t fr, fr_weight;
	fr = heap_new(N);
	fr_weight = heap_new(N);
	
	int i;
	for (i = 0; i< N; i++)
		heap_insert(fr, &fruits[i], compare_h_fruit, NULL);

	/* Set starting possition height */
	int hight_limit = (H%U)? U%H-U : 0;
	int picked_weight = 0;
	
	while ((!heap_is_empty(fr) || !heap_is_empty(fr_weight)) && hight_limit <= H)
	{
		while ((!heap_is_empty(fr)) && ((((fruit*)heap_get_min_key(fr))->height) <= hight_limit))
		{
			heap_insert(fr_weight, (fruit*)heap_get_min_key(fr), compare_w_fruit, NULL);
			heap_remove_min_key(fr, compare_h_fruit, NULL);
		}

		if (!heap_is_empty(fr_weight))
		{
			picked_weight += ((fruit*)heap_get_min_key(fr_weight))->weight;
			heap_remove_min_key(fr_weight, compare_w_fruit, NULL);
		}
		
		hight_limit += U;
	}
	
	
	return picked_weight;
}


int main()
{
	FILE *fin, *fout;
	
	/* Try opening files */
	if (!(fin = fopen(infile, "r"))) 
	{
		fprintf(stderr, "Could not open input file.\n");
		return -1;
	}
	if (!(fout = fopen(outfile, "w"))) 
	{
		fprintf(stderr, "Could not open output file.\n");
		return -1;
	}

	int i, weight;
	
	fscanf(fin, "%d %d %d", &N, &H, &U);
	if (N>NMAX)
	{
		fprintf(stderr, "Count size out of bounds.\n");
		return 1;
	}
	
	fruit* quinces;
	quinces = (fruit*) malloc(N*sizeof(fruit));
	
	for (i = 0; i < N; i++)
		fscanf(fin, "%d %d", &quinces[i].height, &quinces[i].weight);

	weight = solve(quinces);
	
	fprintf(fout, "%d\n", weight);
	
	/* Close files and free memory */
	free(quinces);
	
	fclose(fin);
	fclose(fout);
	
	return 0;
}