#include <iostream>
#include <fstream>
#include <queue>
#include <algorithm>
#include <vector>
#define pb push_back
using namespace std;

struct oaie{
    int dist,blana;

    friend ifstream& operator>>(ifstream& in,oaie& o){
        in>>o.dist>>o.blana;
        return in;
    }
    friend ostream& operator<<(ostream& out,oaie& o){
        out<<o.dist<<" "<<o.blana<<endl;
        return out;
    }
    /*friend bool operator<(const oaie a,const oaie b){
        if(a.dist==b.dist){
            if(a.blana>b.blana) return true;
            return false;
        }
        if(a.dist>b.dist) return true;
        return false;
    }*/
};


int compare(oaie a,oaie b){
    if(a.dist<b.dist)
        return true;
    return false;
}

int main()
{
    ifstream fin("lupu.in");
    ofstream fout("lupu.out");
    int n,x,l;
    fin>>n>>x>>l;
    vector<oaie> v;
    priority_queue <long long int> prinse;
    oaie o;
    for(int i=0;i<n;i++){
        fin>>o;
        v.pb(o);
    }

    sort(v.begin(),v.end(),compare);

    /*for(int i=0;i<v.size();i++){
        cout<<v[i];
    }*/

    int suma=0,i=0,intr=x%l,nr=0;

    while(intr<=x)
    {
        for(i=nr;i<n && v[i].dist<=intr; i++)
            prinse.push(v[i].blana);

        if(!prinse.empty())
        {
            suma+=prinse.top();
            prinse.pop();
        }

        intr+=l;
        nr=i;
    }

    fout<<suma;
    return 0;
}