//#include "stdafx.h"
#include <set>
#include <algorithm>
#define NMAX 100100
using namespace std;
set < long > heap;
long i,j,n,m,k,l,a,b,c;
long long s;
struct kkt
{
	long X,Y,Z;
} x[NMAX];
long cmpf(kkt a , kkt b)
{
	return (a.Z<b.Z);
}
int main()
{
	freopen("lupu.in","r",stdin);
	freopen("lupu.out","w",stdout);
	scanf("%ld%ld%ld",&n,&k,&l);
	for (i=1;i<=n;i++)
	{
		scanf("%ld%d",&x[i].X,&x[i].Y);
		x[i].Z=(k-x[i].X)/l+1;
		if (k<x[i].X)
			x[i].Z=0; 
	}

	sort(x+1,x+n+1,cmpf);
	/*for (i=1;i<=n;i++)
		prlongf("%d %d %d\n",x[i].X,x[i].Y,x[i].Z); */
	m=x[n].Z;
	j=n;
	for (i=m;i>=1;i--)
	{
/*		while (x[j].Z==i&&j>=1)
		{
			heap.insert(-x[j].Y);
			j--;
		} */
		for (j=1;j<=n;j++)
			if (x[j].Z==i)
				heap.insert(-x[j].Y);
		if (heap.begin()!=heap.end())
		{
			s-=*heap.begin();
			heap.erase(heap.begin());
		}
	}
	printf("%lld\n",s);

	return 0;
}