#include <fstream>
#include <algorithm>
#include <queue>

const int MAX_N = 1e5;
std::pair<int, int> a[1 + MAX_N];
std::priority_queue<int> pq;

bool cmp(std::pair<int, int> a, std::pair<int, int> b) {
  return a.first > b.first;
}

int main() {
  std::ifstream fin("lupu.in");
  std::ofstream fout("lupu.out");
  int n, x, l;
  fin >> n >> x >> l;
  for (int i = 1; i <= n; i++) {
    fin >> a[i].first >> a[i].second;
  }
  std::sort(a + 1, a + n + 1, cmp);
  int answer = 0, cnt = 0;
  for (int i = 1; i <= n; i++) {
    int dist = a[i].first + cnt * l;
    if (dist <= x) {
      answer += a[i].second;
      pq.push(-a[i].second);
      cnt++;
    } else if (!pq.empty() && a[i].second > -pq.top()) {
      answer += a[i].second;
      answer -= -pq.top();
      pq.pop();
      pq.push(-a[i].second);
    }
  }
  fout << answer;
  return 0;
}