#include <bits/stdc++.h>
#define pii pair<int,int>
using namespace std;

ifstream fin("lupu.in");
ofstream fout("lupu.out");

vector <pii> v;

//bool cmp(pii a,pii b)
//{
  //  return a.first > b.first;
//}

int main()
{
    int n,x,L,lana = 0;
    fin >> n >> x >> L;
    for (int i = 0; i< n; i++)
    {
        int a,b;
        fin >> a >> b;
        v.push_back({a,b});
    }
    sort(v.begin(),v.end());

    set <int> Q;
    int d = (x%L);
    int i = 0;
    while (v[i].first <= d && i < n)
    {
        Q.insert({v[i].second});
        if (v[i+1].first > d || i == n-1)
        {
            lana += *Q.rbegin();
            //cout << "\n" << d << " " << Q.rbegin()->first << "\n";
            while (v[i+1].first > d)
            {
                lana += *Q.rbegin();
                Q.erase(Q.rbegin());
                d += L;
            }
            Q.erase(Q.rbegin());
        }
        i++;
    }
    fout << lana;
    return 0;
}