#include <iostream>
#include <fstream>
#include <queue>
#include <algorithm>
using namespace std;
ifstream f("lupu.in");
ofstream g("lupu.out");
typedef pair <unsigned long long int,unsigned long long int> copil;
copil v[200001],aux;
priority_queue<unsigned long long int> coada;
int n,ok;
unsigned long long int x,l2,suma;
int partitie (int l,int r)
{
    int pivot=v[r].first,poz=l-1;
    for(int j=l;j<=r;j++)
    {
        if(v[j].first<=pivot)
        {
            poz++;
            aux=v[poz];
            v[poz]=v[j];
            v[j]=aux;
        }
    }
    return poz;
}
void quicksort(int l,int r)
{
    if(l<r)
    {
     int pivot=partitie(l,r);
     quicksort(l,pivot-1);
     quicksort(pivot+1,r);
    }
}
int main()
{
   f>>n>>x>>l2;
   for(int i=0;i<n;i++)
    f>>v[i].first>>v[i].second;
  // quicksort(1,n);
    sort(v, v+n);
int u=x%l2,d=0;
for(int i=u;i<=x;i+=l2)
{
    for(;v[d].first<=i&&d<=n;++d)
        coada.push(v[d].second);
    if(!coada.empty())
    {
        suma+=coada.top();
        coada.pop();
    }
}
    g<<suma;
    return 0;
}