#include <algorithm>
#include <fstream>
using namespace std;

#define g first
#define h second

const int NMAX=100001;

int N,H,U,a[NMAX];

pair<int,int> G[NMAX];

int main()
{
	int i,j;
	ifstream fin("gutui.in");
	fin>>N>>H>>U;
	for (i=1;i<=N;++i) fin>>G[i].h>>G[i].g;

	sort(G+1,G+N+1);
	int na=0;
	for (i=N;i>0;--i)
	{
		int mmari=0;
		for (j=1;j<=na;++j)
			if (G[a[j]].h >= G[i].h) ++mmari;
		if (mmari*U + G[i].h <=H) a[++na]=i;
	}

	int sum=0;
	for (i=1;i<=na;++i) sum+=G[a[i]].g;

	ofstream fout("gutui.out");
	fout<<sum;

	return 0;
}