#include <bits/stdc++.h>
using namespace std;
using ll = long long;
//fk const time bro
//#define int long long
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
int n, m, k;
int a[100005][3];
vector <pair <int, int> > to[100005];
pair <ll, int> t[1<<19];
ll lazy[1<<19];
void build(int v, int tl, int tr){
if(tl == tr)t[v] = {0, 0};
else {
build(v<<1, tl, (tl+tr)>>1);
build(v<<1|1, ((tl+tr)>>1) + 1, tr);
t[v] = min(t[v<<1], t[v<<1|1]);
}
lazy[v] = 0;
}
inline void push(int v, int tl, int tr) {
int tm = (tl + tr) >> 1;
t[v<<1].first += lazy[v];
lazy[v<<1] += lazy[v];
t[(v<<1)+1].first += lazy[v];
lazy[(v<<1)+1] += lazy[v];
lazy[v] = 0;
}
inline void update(int v, int tl, int tr, int l, int r, ll addend) {
if (l > r)
return;
push(v, tl, tr);
if (l == tl && tr == r) {
t[v].first += addend;
lazy[v] += addend;
} else {
push(v, tl, tr);
int tm = (tl + tr) >> 1;
update(v<<1, tl, tm, l, min(r, tm), addend);
update((v<<1)+1, tm+1, tr, max(l, tm+1), r, addend);
t[v] = min(t[v<<1], t[(v<<1)+1]);
}
}
inline void upos (int v, int tl, int tr, int p, int V) {
if (p < tl || p > tr) return;
push(v, tl, tr);
if (tl == tr) {
t[v].second = V;
}
else {
push(v, tl, tr);
int tm = (tl + tr) >> 1;
upos(v<<1, tl, tm, p, V);
upos((v<<1)+1, tm+1, tr, p, V);
t[v] = min(t[v<<1], t[(v<<1)+1]);
}
}
inline pair <ll, int> query(int v, int tl, int tr, int l, int r) {
if (l > r)
return {1e18, 1e9};
if (l == tl && tr == r)
return t[v];
push(v, tl, tr);
int tm = (tl + tr) >> 1;
return min(query(v<<1, tl, tm, l, min(r, tm)),
query((v<<1)+1, tm+1, tr, max(l, tm+1), r));
}
int32_t main () {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n >> m >> k;
ll tot = 0;
for (int i = 1; i <= m; i++) {
cin >> a[i][0] >> a[i][1] >> a[i][2];
to[a[i][1]].push_back({a[i][0], a[i][2]});
tot += a[i][2];
}
if (k == 1) {
vector < vector <ll> > dp(n + 1, vector <ll>(k + 3, 0));
dp[0][0] = 0;
for (int i = 1; i <= n; i++) dp[i][0] = 1e18;
for (int i = 1; i <= k + 1; i++) {
build(1, 0, n);
for (int j = 0; j <= n; j++) {
update(1, 0, n, j, j, dp[j][i - 1]);
}
for (int j = 1; j <= n; j++) {
dp[j][i] = 1e18;
/*
ll c = 0;
for (int l = j - 1; l >= 0; l--) {
for (auto [a, b] : fr[l + 1]) if (a <= j) c += b;
//for (int x = 1; x <= m; x++) if (a[x][0] > l && a[x][1] <= j) c += a[x][2];
dp[j][i] = min(dp[j][i], dp[l][i - 1] + c);
}
*/
for (auto [a, b] : to[j]) update(1, 0, n, 0, a - 1, b);
dp[j][i] = query(1, 0, n, 0, j - 1).first;
}
}
cout << dp[n][k + 1];
return 0;
}
//let dp[i][j] = min. cost such that there are j disjoint segments in [1, i], and there are no active teleporters that start and end at the same segment.
k = min(k, n);
ll lo = 0, hi = tot / (k + 1) + 1, ans = hi, T = 1e18;
vector < pair <ll, int> > dp(n + 1);
while (lo <= hi) {
ll mid = (lo + hi) >> 1;
//build(1, 0, n);
for (int j = 0; j <= n * 4 + 5; j++) t[j] = {0, 0}, lazy[j] = 0;
dp[0] = {0, 0};
for (int i = 1; i <= n; i++) {
//for (auto [a, b] : to[i]) root->upd(0, a - 1, b);
for (auto &[a, b] : to[i]) update(1, 0, n, 0, a - 1, b);
//auto res = root->qry(0, i - 1);
auto res = query(1, 0, n, 0, i - 1);
dp[i] = {res.first + mid, res.second + 1};
//root->upd(i, i, dp[i].first);
//root->upos(i, dp[i].second);
update(1, 0, n, i, i, dp[i].first);
upos(1, 0, n, i, dp[i].second);
}
if (dp[n].second <= k + 1) ans = mid, hi = mid - 1;
else lo = mid + 1;
}
//cout << ans << '\n';
//root = new node(0, n);
for (int j = 0; j <= n * 4 + 5; j++) t[j] = {0, 0}, lazy[j] = 0;
dp[0] = {0, 0};
for (int i = 1; i <= n; i++) {
//for (auto [a, b] : to[i]) root->upd(0, a - 1, b);
for (auto &[a, b] : to[i]) update(1, 0, n, 0, a - 1, b);
//auto res = root->qry(0, i - 1);
auto res = query(1, 0, n, 0, i - 1);
dp[i] = {res.first + ans, res.second + 1};
//root->upd(i, i, dp[i].first);
//root->upos(i, dp[i].second);
update(1, 0, n, i, i, dp[i].first);
upos(1, 0, n, i, dp[i].second);
}
//cout << dp[n].first << ' ' << dp[n].second << '\n';
cout << dp[n].first - (k + 1) * ans << '\n';
}
