#include <bits/stdc++.h>
#define ll long long
#define int ll
#define ld long double
#define pii pair<int, int>
#define tpl tuple<int, int, int>
#define piv pair<int, vector<int>>
#define eb emplace_back
#define oo INT_MAX / 2
#define OO LLONG_MAX / 2
using namespace std;

const string fn("lupu");

ifstream in(fn + ".in");
ofstream out(fn + ".out");

#define cin in
#define cout out

int N, X, L;
map<int, vector<int>> M;
priority_queue<int> pqans;

void solve()
{
    cin >> N >> X >> L;
    /// assert(L > 0);
    for (int i = 1; i <= N; i++)
    {
        int d, a;
        cin >> d >> a;

        int r = 0;

        r = (X - d) / L;
        M[r].eb(a);

        /// cout<<a<<' '<<d<<' '<<r<<'\n';
    }

    int timer = M.rbegin()->first, ans = 0;
    auto x=M.rbegin();

    while (timer >= 0 and x!=M.rend())
    {
        while(x!=M.rend() and x->first>=timer)
        {
            auto pq = x->second;
            while (pq.size())
                pqans.emplace(pq.back()), pq.pop_back();
            x++;
        }
        if(pqans.size())
            ans += pqans.top(), pqans.pop();
        timer--;
    }

    cout << ans;
}

signed main()
{
    int q = 1;

    /// cin >> q;
    while (q--)
        solve();
    return 0;
}