#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <vector>
#include <climits>
using namespace std;
using ll = long long;
using db = long double;
using str = string;
using pi = pair <int, int>;
using pl = pair <ll, ll>;
using pd = pair <db, db>;
#define mp make_pair
#define ff first
#define ss second
template <class T> using V = vector <T>;
using vi = V <int>;
using vb = V <bool>;
using vl = V <ll>;
using vd = V <db>;
using vs = V <str>;
using vpi = V <pi>;
using vpl = V <pl>;
using vpd = V <pd>;
template <class T> using PQ = priority_queue <T>;
#define sz(x) (int) size(x)
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define srt(x) sort(all(x))
#define rsz resize
#define ins insert
#define pb push_back
#define emb emplace_back
#define em emplace
#define ft front()
#define bk back()
#define lb lower_bound
#define ub upper_bound
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define F0R(i, a) FOR(i, 0, a-1)
#define ROF(i, a, b) for (int i = (b); i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a-1)
#define each(e, x) for (auto &e : x)
ll cdiv(ll a, ll b) { return ceil((db) a / b); }
ll fdiv(ll a, ll b) { return floor((db) a / b); }
template <class T> bool ckmin(T &a, const T &b) {
return b < a ? a = b, 1 : 0;
}
template <class T> bool ckmax(T &a, const T &b) {
return b > a ? a = b, 1 : 0;
}
template <typename T, typename = void>
struct is_iterable : false_type {};
template <typename T>
struct is_iterable<T, void_t<decltype(begin(declval<T>())), decltype(end(declval<T>()))>> : true_type {};
void err(string name) {}
template <typename T, typename... Args>
void err(string name, T val, Args... args) {
size_t pos = name.find(',');
string first = (pos == string::npos) ? name : name.substr(0, pos);
string rest = (pos == string::npos) ? "" : name.substr(pos + 2);
cout << first << " = ";
if constexpr (is_iterable<T>::value && !is_same_v<T, string>) {
cout << "{";
bool fst = true;
for (auto const& x : val) {
if (!fst) cout << ", ";
cout << x;
fst = false;
}
cout << "}";
} else {
cout << val;
}
if (rest != "") {
cout << " | ";
err(rest, args...);
} else {
cout << '\n';
}
}
#ifdef LOCAL
#define dbg(...) cout << "[" << __FUNCTION__ << ":" << __LINE__ << "] ", err(#__VA_ARGS__, __VA_ARGS__)
#else
#define dbg(...) 67
#endif
void setIO(string name = "") {
ios::sync_with_stdio(0), cin.tie(0);
if (sz(name)) {
freopen((name + ".in").c_str(), "r", stdin);
freopen((name + ".out").c_str(), "w", stdout);
}
}
const ll INF = 1e18;
const pi d[4] = {{0, -1}, {0, 1}, {1, 0}, {-1, 0}};
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
const int mod = 998244353; // 1e9+7;
const int mxN = 1e5+5;
struct SEG {
pl seg[4*mxN];
ll lz[4*mxN];
void build(int l, int r, int u) {
if (l == r) seg[u] = mp(0, 0), lz[u] = 0;
else {
int m = l + (r-l)/2;
build(l, m, u<<1);
build(m+1, r, u<<1|1);
seg[u] = mp(0, 0), lz[u] = 0;
}
}
void push(int u) {
seg[u<<1].ff += lz[u];
seg[u<<1|1].ff += lz[u];
lz[u<<1] += lz[u];
lz[u<<1|1] += lz[u];
lz[u] = 0;
}
void upd(int l, int r, int x, int y, pl k, int u) {
if (r < x || l > y) return;
else if (x <= l && r <= y) seg[u].ff += k.ff, seg[u].ss += k.ss, lz[u] += k.ff;
else {
push(u);
int m = l + (r-l)/2;
upd(l, m, x, y, k, u<<1);
upd(m+1, r, x, y, k, u<<1|1);
seg[u] = min(seg[u<<1], seg[u<<1|1]);
}
}
pl qr(int l, int r, int x, int y, int u) {
if (r < x || l > y) return mp(INF, INF);
if (x <= l && r <= y) return seg[u];
else {
push(u);
int m = l + (r-l)/2;
return min(qr(l, m, x, y, u<<1), qr(m+1, r, x, y, u<<1|1));
}
}
} T;
int main() {
setIO();
int n, m, k; cin >> n >> m >> k;
V <tuple <int, int, ll>> v(m);
for (auto &[r, l, c] : v) cin >> l >> r >> c;
srt(v);
auto calc = [&] (ll ld) {
T.build(0, n+1, 1);
pl dp[n+2];
dp[0] = mp(0, 0);
int it = 0;
for (int i = 1; i <= n+1; i++) {
while (it < m && get<0>(v[it]) < i) {
T.upd(0, n+1, 0, get<1>(v[it]), mp(get<2>(v[it]), 0), 1);
it++;
}
dp[i] = T.qr(0, n+1, 0, i-1, 1);
dp[i].ff += ld, dp[i].ss++;
T.upd(0, n+1, i, i, dp[i], 1);
if (ld == 8) dbg(i, dp[i].ff, dp[i].ss);
}
return dp[n+1];
};
ll L = 0, R = 1e14, ans = 0;
while (L <= R) {
ll m = L + (R-L)/2;
pl x = calc(m);
if (x.ss-1 <= k) ans = m, R = m-1;
else L = m+1;
}
dbg(ans);
pl val = calc(ans);
dbg(val.ff, val.ss);
cout << val.ff - val.ss * ans - (k - (val.ss - 1)) * ans << '\n';
}
