#include <iostream>
#include <fstream>
#include <algorithm>
#include <queue>
#include <climits>

using namespace std;

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

const int NMax = 100000 + 5;

int N,X,L,sol;
priority_queue<int> h;

struct elem {
    int dist,val;
}v[NMax];

bool cmp (elem a,elem b) {
    return a.dist<b.dist;
}

int main() {
    in>>N>>X>>L;

    for (int i=1;i<=N;++i) {
        in>>v[i].dist>>v[i].val;
    }

    sort(v+1,v+N+1,cmp);

    int minDist = v[1].dist;
    if (minDist > X) {
        cout<<0;
        return 0;
    }

    int rem = (X-minDist+1)/L;
    int distFromWolf = rem*L;

    int i = 1;
    while (0<=distFromWolf) {
        while (i<=N && v[i].dist + distFromWolf <= X) {
            h.push(v[i++].val);
        }

        if (!h.empty()) {
            sol += h.top();
            h.pop();
        }

        distFromWolf -= L;
    }

    out<<sol;
    return 0;
}