#include <iostream>
#include <fstream>
#include <queue>
#include <algorithm>
using namespace std;
int n, d, l, i, nr, sum;
pair<int,int> v[100005];
priority_queue <int> q;
int main()
{
    ifstream cin("lupu.in");
    ofstream cout("lupu.out");
    cin>>n>>d>>l;
    for(i=1; i<=n; i++)
        cin>>v[i].first>>v[i].second;
    sort(v+1,v+n+1);
    for(i=1; i<=n&&v[i].first<=d; nr++)
    {
        while(i<=n&&v[i].first<=nr*l)
            q.push(v[i].second),i++;
        if(!q.empty())
            sum+=q.top(),q.pop();
    }
    cout<<sum;
    return 0;
}