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

ifstream fin("lupu.in");
ofstream fout("lupu.out");
class cmp
{
public:
	inline bool operator()(const pair<long long, long long> &A, const pair<long long, long long> &B)
	{
		return A.first > B.first;
	}
	inline bool operator()(const long long &A, const long long &B)
	{
		return A <= B;
	}
};
long long N, DMax, D, GG;
vector< pair<long long, long long> > A;
vector<long long> H;

int main()
{
	fin >> N >> DMax >> D;
	A.resize(N + 3, make_pair(0, 0));
	for (long long i = 1; i <= N; ++i)
	{
		fin >> A[i].first >> A[i].second;
		if (A[i].first > DMax) A[i].first = 0;
		else A[i].first = (DMax - A[i].first) / D + 1;
	}
	sort(A.begin() + 1, A.end(), cmp());
	for (long long i = 1; i <= N; )
	{
		if (A[i].first == 0) break;
		for (long long foo = i; A[foo].first == A[i].first; H.push_back(A[i].second), push_heap(H.begin(), H.end(), cmp()), ++i);
		if (H.size()) GG += H.front();
		pop_heap(H.begin(), H.end(), cmp()), H.pop_back();
	}
	fout << GG << '\n';
	fout.close();
	return 0;
}