#include "bits/stdc++.h"
#define int long long
#define vi vector<int>
#define pb push_back
#define pii pair<int, int>
using namespace std;
const int MAXN = 1e5 + 10;
int n, m, k;
int s[MAXN], t[MAXN], c[MAXN];
vi fr[MAXN];
struct Node {
int lazy = 0;
int mn = 0, mnidx;
} seg[4 * MAXN];
void init(int l, int r, int idx) {
seg[idx].mnidx = l;
seg[idx].mn = seg[idx].lazy = 0;
if (l == r) {
return;
}
int mid = (l + r) >> 1;
init(l, mid, 2 * idx + 1);
init(mid + 1, r, 2 * idx + 2);
}
void push_down(int idx) {
if (!seg[idx].lazy) return;
for (int i=(idx<<1) + 1; i<=(idx<<1) + 2; i++) {
seg[i].lazy += seg[idx].lazy;
seg[i].mn += seg[idx].lazy;
}
seg[idx].lazy = 0;
}
void push_up(int idx) {
seg[idx].mn = min(seg[(idx<<1) + 1].mn, seg[(idx<<1) + 2].mn);
seg[idx].mnidx = (
seg[idx].mn == seg[(idx<<1) + 1].mn ?
seg[(idx<<1) + 1].mnidx : seg[(idx<<1) + 2].mnidx
);
}
void u(int l, int r, int constl, int constr, int idx, int val) {
if (l <= constl && constr <= r) {
seg[idx].lazy += val;
seg[idx].mn += val;
return;
}
push_down(idx);
int mid = (constl + constr) >> 1;
if (mid < l || r < constl) u(l, r, mid+1, constr, (idx<<1) + 2, val);
else if (constr < l || r < mid+1) u(l,r , constl, mid, (idx<<1) + 1, val);
else {
u(l, r, constl, mid, (idx<<1) + 1, val);
u(l, r, mid+1, constr, (idx<<1) + 2, val);
}
push_up(idx);
}
pii qu(int l, int r, int constl, int constr, int idx) {
if (l <= constl && constr <= r) return {seg[idx].mn, seg[idx].mnidx};
int mid = (constl + constr) >> 1;
push_down(idx);
if (mid < l || r < constl) return qu(l, r, mid+1, constr, (idx<<1) + 2);
else if (constr < l || r < mid+1) return qu(l, r, constl, mid, (idx<<1) + 1);
else {
return
min(
qu(l, r, constl, mid, (idx<<1) + 1),
qu(l, r, mid+1, constr, (idx<<1) + 2)
);
}
}
void range_add(int l, int r, int v) {
u(l, r, 0, n, 0, v);
}
pii query(int l, int r) {
return qu(l, r, 0, n, 0);
}
pii min_intercept(int slope) {
pii dp[n+1];
dp[0] = {0, 0};
init(0, n, 0);
for (int i=1; i<=n; i++) {
pii bruh = query(0, i - 1);
int res = bruh.first, idx = bruh.second;
dp[i] = {res - slope, dp[idx].second + 1};
range_add(i, i, dp[i].first);
for (int x: fr[i]) {
range_add(0, s[x], c[x]);
}
}
return dp[n];
}
void solve() {
cin >> n >> m >> k;
for (int i=1; i<=n; i++) fr[i].clear();
for (int i=1; i<=m; i++) {
cin >> s[i] >> t[i] >> c[i];
fr[t[i]].pb(i);
}
m++;
n++;
k++;
s[m] = t[m] = n;
c[m] = 1e18;
int lb = -1e14, rb = -1;
while (lb < rb) {
int mid = lb + ((rb - lb + 1) >> 1);
if (min_intercept(mid).second > k) rb = mid - 1;
else lb = mid;
}
pii fin = min_intercept(lb);
cout << max(0ll, fin.first + k * lb) << "\n";
}
int32_t main() {
ios::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
for (int i=1; i<=t; i++) solve();
}
