#include <iostream>
#include<fstream>
#include<queue>
#include<algorithm>
#define Nmax 100001
using namespace std;
int n,x,L;
priority_queue <int> q;
long long sol;
struct oaie
{
    int dist,lana;
};
oaie v[Nmax];
inline bool cmp (const oaie A, const oaie B )
{
     if (A.dist == B.dist)
        return A.lana < B.lana;
     return A.dist < B.dist ;
}
void citire()
{
    int i,d,a;
    ifstream fin("lupu.in");
    fin>>n>>x>>L;
    for(i=1;i<=n;++i)
    {
        fin>>d>>a;
        d=(x-d)/L + 1;
        v[i].dist=d;
        v[i].lana=a;
    }
    fin.close();
    sort(v+1, v+n+1, cmp);
}
void solve()
{

    int i,timp;
    i=n;
    for(timp=v[n].dist;timp>=1;--timp)
    {
        while(i>0 && v[i].dist==timp)
        {
            q.push(v[i].lana);
            --i;
        }
        if(!q.empty())
        {
            sol+=q.top();
            q.pop();
        }
        else
        {
            if(i>0)
                timp=v[i].dist + 1;
            else
                return;
        }
    }
}
int main()
{
    citire();
    solve();
    ofstream fout("lupu.out");
    fout<<sol<<"\n";
    fout.close();
    return 0;
}