#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#define MAXN 100000
#define DEBUG 0

#define PR(x) (x-1)/2
#define CH1(x) (x*2)+1
#define CH2(x) (x*2)+2

using namespace std;

vector<vector<int>> v;
int nrb = 0;

struct Option {
  int x;
  int id, pos;
};

Option hp[MAXN];
int hpl = 0;

void swap(int a, int b){
  Option aux = hp[a];
  hp[a] = hp[b];
  hp[b] = aux;
}

void downheap(int x){
  int chosen;

  if(CH1(x) >= hpl)
    return;
  if(CH2(x) >= hpl || hp[CH2(x)].x > hp[CH1(x)].x){
    chosen = CH1(x);
  } else
    chosen = CH2(x);

  if(hp[x].x < hp[chosen].x){
    swap(chosen, x);
    downheap(chosen);
  }
}
void upheap(int x){
  if(x == 0)
    return;

  if(hp[x].x > hp[PR(x)].x){
    swap(x, PR(x));
    upheap(PR(x));
  }
}
void remove(int x){
  hpl --;
  hp[x] = hp[hpl];

  if(hpl > x)
    downheap(x);
}

static inline int bracket(int x, int y){
  if(x % y == 0)
    return x / y;
  return x / y + 1;
}

int main(){
  int n, x, y;

  ifstream fin ("lupu.in");
  fin >> n >> x >> y;

  nrb = bracket(x, y) + 1;
  v.resize(nrb);

  for(int i = 0; i < n; i ++){
    int d, l;
    fin >> d >> l;
    v[bracket(d, y)].push_back(l);
  }
  fin.close();

  for(int i = 0; i < nrb; i ++)
    sort(v[i].begin(), v[i].end());

  if(DEBUG){
    for(int i = 0; i < nrb; i ++){
      printf("%d: ", i);
      for(int j = 0; j < (int)v[i].size(); j ++){
        printf("%d ", v[i][j]);
      }
      printf("\n");
    }
    printf("\n");
  }
  
  int sum = 0;
  for(int i = 0; i < nrb; i ++){
    if(v[i].size() > 0){
      Option o = {v[i][ v[i].size() - 1 ], i, (int)v[i].size() - 1};
      hp[hpl] = o;
      upheap(hpl);
      hpl ++;
    }

    if(hpl > 0){
      if(DEBUG)
        cout << hp[0].x << " " << hp[0].id << " " << hp[0].pos << "\n";
      sum += hp[0].x;
      if(hp[0].pos != 0){
        hp[0].pos --;
        hp[0].x = v[hp[0].id][hp[0].pos];
        downheap(0);

      } else
        remove(0);
    }
  }

  ofstream fout ("lupu.out");
  fout << sum << endl;
  fout.close();

  return 0;
}