#include <fstream>
#include <stdlib.h>

using namespace std;

struct gutuie {
	int g;    // greutatea
    int n;    // nr max de gutui culese anterior pt care gutuia ramane accesibila, numit "nivel"
	int idx;  // indexul 
};

#define S (sizeof(gutuie))

ifstream in ("gutui.in");
ofstream out("gutui.out");
int n, h, u, r = 0, nr = 0, *del;
gutuie *gutui, *gutui2;

// comparara dupa nivel
int cmp_n(const void* fp1, const void* fp2) {
	gutuie* f1 = (gutuie*)fp1;
	gutuie* f2 = (gutuie*)fp2;
	int r = f1->n - f2->n;
	return (r == 0 ? f2->g - f1->g : r);
}

// comparara dupa greutate
int cmp_g(const void* fp1, const void* fp2) {
	gutuie* f1 = (gutuie*)fp1;
	gutuie* f2 = (gutuie*)fp2;
	int r = f1->g - f2->g;
	return (r == 0 ? f1->n - f2->n : r);
}


void print() {
     for (int i = 0; i < n; i++) {
         printf("%9d %d %d             %9d %d %d\n",  gutui[i].g, gutui[i].n, gutui[i].idx, gutui2[i].g, gutui2[i].n, gutui2[i].idx);
     }
     printf("\n");
}



int main() {
	
	in >> n >> h >> u;
	gutui = new gutuie[n];
	int ch, cg, cn, cnr, i, j, k, rem;

	/***********************************************************************************************************
	 * - citire din fisier 
	 * - o prima selectie - selectatrea cazurilor convenabile, adica
	 *						eliminarea gutuilor la care nu se poate ajunge din prima , adica nivelul < 0 si
	 *						a celor cu greutate nula (daca exista)
	 * - nr gutuilor ramase dupa aceasta prima selectie fiind nr <= n
	 *
	 ***********************************************************************************************************/
	
    r = 0;
	for (i = 0; i < n; i++) {
		in >> ch >> cg;       // citire inaltime si greutate
		cn = (h - ch);    // calcul nivel
		if (cn >= 0 && cg > 0) { // se adauga numai cazurile convenabile 
			r += cg;
			gutui[nr].g = cg;
			gutui[nr].n = cn / u;
			nr++;
		}
    }

	n = nr; 
	if (n <= 1) {
		out << r;
		return 0;
	}

	qsort(gutui, n, S, cmp_g);
	for (i = 0; i < n; i++)
		gutui[i].idx = i;
	qsort(gutui, n, S, cmp_n);
	
	int maxd = -gutui[0].n, // nr maxim de elem eliminat 
		maxi =  0,         // indicele 
		maxn;      
	for (i = 1; i < n; i++) {
		if (i - gutui[i].n >= maxd) {
			maxd = i - gutui[i].n;
			maxi = i;
		}
	}

	j = n - 1;
	while (gutui[j].n >= j && j >= 0) {
		if (gutui[j].idx < maxd)
			maxd++;
		n--;
		j--;
	}


	for (i = maxi + 1; i < n; i++)
		if (gutui[i].idx < maxd)
			maxd++;

	if (j <= 1) {
		out << r;
		return 0;
	}

	maxn = gutui[n - 1].n;
	for (i = 0; i <= maxi; i++)
		if (gutui[i].idx < maxd)// || (gutui2[i].n == maxn && gutui2[i].n >= i))
			r -= gutui[i].g;

	out << r;
	return 0;
}