#include <bits/stdc++.h>
using namespace std;

struct sheep {
    int d, c;
} v[100001];

bool comp(sheep a, sheep b) {
    return a.d > b.d;
}

int n, x, l;

int main() {
    ifstream cin("lupu.in");
    ofstream cout("lupu.out");
    cin >> n >> x >> l;
    for (int i = 1; i <= n; ++i) {
        cin >> v[i].d >> v[i].c;
    }
    sort(v + 1, v + n + 1, comp);
    long long ans = 0, dist = 0;
    int maxVal = 0;
    for (int i = 1; i <= n; ++i) {
        if (v[i].d + dist + l > x && v[i].d + dist <= x) {
            maxVal = max(maxVal, v[i].c);
            if (i + 1 <= n && v[i + 1].d + dist + l <= x) {
                ans += maxVal;
                maxVal = 0;
                dist += l;
            }
        }
        if (v[i].d + dist + l <= x) {
            ans += v[i].c;
            dist += l;
        }
    }
    if (maxVal != 0) {
        ans += maxVal;
    }
    cout << ans;
}