#include <bits/stdc++.h>

using namespace std;

#if 1
    #define pv(x) cout<<#x<<" = "<<(x)<<"; ";cout.flush()
    #define pn cout<<endl
#else
    #define pv(x)
    #define pn
#endif

#ifdef INFOARENA
    ifstream in("lupu.in");
    ofstream out("lupu.out");
#else
    #define in cin
    #define out cout
#endif

using ll = long long;
using ull = unsigned long long;
using uint = unsigned int;
using ld = long double;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using pld = pair<ld, ld>;
#define pb push_back
const double PI = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862;
const int inf_int = 1e9 + 5;
const ll inf_ll = 1e18 + 5;
const int NMax = 1e2 + 5;
const int dx[] = {-1,0,0,+1}, dy[] = {0,-1,+1,0};

int main() {
    cin.sync_with_stdio(false);
    cin.tie(0);
    
    ll N,X,L;
    in >> N >> X >> L;
    vector<pll> v(N);
    for (auto& p : v) {
        in >> p.first >> p.second;
    }

    sort(v.begin(), v.end());

    multiset<ll> wool;
    int pos = 0;
    ll ans = 0;
    for (ll i = N-1; i >= 0; --i) {
        while (pos < N && v[pos].first + i * L <= X) {
            wool.insert(v[pos].second);
            pos += 1;
        }

        if (wool.size()) {
            ans += *(--wool.end());
            wool.erase(--wool.end());
        }
    }

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