#include <iostream>
#include <fstream>
#include <cmath>
#include <algorithm>
#include <queue>
using namespace std;

ifstream f("lupu.in");
ofstream g("lupu.out");

int maxi(pair<int,int>v[100000],int b){
int i;
int rez;//indicele elem maxim din v
int maxim=0;
for(i=0;i<=b;i++)
    if(v[i].second>maxim)
    {
        rez=i;
        maxim=v[i].second;
    }
return rez;
}

int cmp(const pair<int,int>&p,const pair<int,int>&q)
{
    if(p.first==q.first)
        return(p.second<q.second);
    return p.first<q.first;
}

int main()
{
    int n,x,l,i;
     priority_queue <long long int> oi;
    pair<int,int>v[100000];
    f>>n>>x>>l;
    for(i=0;i<n;i++)
        f>>v[i].first>>v[i].second;

     sort(v,v+n,cmp);//sortez in functie de distanta-crescator

  int s=0;
int nr_intervale=x/l;
if(x%l!=0)
    nr_intervale++;

    while(nr_intervale<=x)
{
 for(;i<n&&v[i].first<=nr_intervale;++i)
        oi.push(v[i].second);
 if(!oi.empty() )
    {
        s+=oi.top();
        oi.pop();
    }
       nr_intervale+=l;
}
g<<s;
return 0;}