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#include <bits/stdc++.h>
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using namespace std;
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typedef long long ll;
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const int N = 5e5 + 100;
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struct People {
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    int l, r, w;
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    friend bool operator<(const People a, const People b) { return a.w < b.w; }
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} a[N];
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priority_queue<People> pq;
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int n, m, k;
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ll f[N];
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signed main() {
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    cin >> n >> m >> k;
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    for (int i = 1; i <= n; i++) {
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        cin >> a[i].l >> a[i].r >> a[i].w;
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    }
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    sort(a + 1, a + n + 1,
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         [](const People a, const People b) { return a.l < b.l; });
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    int ptr = 0;
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    for (int i = 1; i <= m; i++) {
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        while (ptr != n && a[ptr + 1].l <= i - k + 1) {
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            pq.push(a[++ptr]);
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        }
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        f[i] = f[i - 1];
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        while (!pq.empty()) {
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            People top = pq.top();
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            if (top.r < i) {
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                pq.pop();
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                continue;
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            }
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            f[i] = max(f[i], f[i - k] + top.w);
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            break;
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        }
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    }
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    cout << f[m];
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    return 0;
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}