#include <bits/stdc++.h>
#define NMAX 100005
#define INF 2e9

using namespace std;

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

int n, x, l;
pair <int, int> v[NMAX];

inline int turns(pair <int, int> a) {

    int turns_a = 0;

    if (a.second <= x)
        turns_a = 1 + (x - a.second) / l;

    return turns_a;
}

inline bool cmp(pair <int, int> a, pair <int , int> b) {

    return turns(a) < turns(b);
}

int main()
{
    in >> n >> x >> l;

    for (register int i = 1; i <= n; ++i)
        in >> v[i].second >> v[i].first;

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

    multiset <int> s;
    long long sum = 0;

    int i = n, prev = turns(v[n]);
    while (i >= 1) {
        if (prev != turns(v[i])) {

            while (prev - turns(v[i]) && !s.empty()) {
                
                sum -= (*s.begin());
                s.erase(s.begin());
                --prev;
            }

            prev = turns(v[i]);
        }

        s.insert(-v[i].first);
        --i;
    }

    while (prev && !s.empty()) {
        sum -= (*s.begin());
        s.erase(s.begin());
        --prev;
    }

    out << sum << '\n';
    return 0;
}