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

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

int cmp(const pair<int,int>&p,const pair<int,int>&q)
{
    return p.first<q.first;
}
 priority_queue <long long int> oi;

int main()
{
    int n,x,l,i;
    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

  long long int s=0, nr_intervale=x%l;

    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;}