#include <iostream>
#include <fstream>
#include <algorithm>
#include <queue>
#define nmx 100005
#define ll long long

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

ll n, i, j, nr, dmx, incr, pos, rez;

struct Per {
    
    ll id, ln;
    bool operator<(const Per &alt)const
    {   return id > alt.id;    }
} v[nmx];

priority_queue<int> pq;

int main () {
    
    fin >> n >> dmx >> incr;
    for(i = 1; i <= n; i++) {
        
        fin >> v[i].id >> v[i].ln;
        if (v[i].id <= dmx)  v[i].id = (dmx - v[i].id) / incr + 1;
        else    v[i].id = 0;
    }
    
    sort(v + 1, v + n + 1);
    
    v[++n] = {0, 0};
    
    v[0] = v[1];
    for (i = 1; i <= n + 1; i++)    {
        
        if (v[i].id != v[i-1].id)   {
            
            nr = min(v[i-1].id - v[i].id, (ll)pq.size());
            while (nr--)    {
                rez += pq.top();
                pq.pop();
            }
        }
        pq.push((int)v[i].ln);
    }
    
    fout << rez << "\n";
}