#include <bits/stdc++.h>
using namespace std;
template <typename T, typename T1>
ostream &operator<<(ostream &out, pair<T, T1> obj) {
  out << "(" << obj.first << "," << obj.second << ")";
  return out;
}
template <typename T, typename T1>
ostream &operator<<(ostream &out, map<T, T1> cont) {
  typename map<T, T1>::const_iterator itr = cont.begin();
  typename map<T, T1>::const_iterator ends = cont.end();
  for (; itr != ends; ++itr) out << *itr << " ";
  out << endl;
  return out;
}
template <typename T>
ostream &operator<<(ostream &out, set<T> cont) {
  typename set<T>::const_iterator itr = cont.begin();
  typename set<T>::const_iterator ends = cont.end();
  for (; itr != ends; ++itr) out << *itr << " ";
  out << endl;
  return out;
}
template <typename T>
ostream &operator<<(ostream &out, multiset<T> cont) {
  typename multiset<T>::const_iterator itr = cont.begin();
  typename multiset<T>::const_iterator ends = cont.end();
  for (; itr != ends; ++itr) out << *itr << " ";
  out << endl;
  return out;
}
template <typename T,
          template <typename ELEM, typename ALLOC = allocator<ELEM>> class CONT>
ostream &operator<<(ostream &out, CONT<T> cont) {
  typename CONT<T>::const_iterator itr = cont.begin();
  typename CONT<T>::const_iterator ends = cont.end();
  for (; itr != ends; ++itr) out << *itr << " ";
  out << endl;
  return out;
}
template <typename T, unsigned int N, typename CTy, typename CTr>
typename enable_if<!is_same<T, char>::value, basic_ostream<CTy, CTr> &>::type
operator<<(basic_ostream<CTy, CTr> &out, const T (&arr)[N]) {
  for (auto i = 0; i < N; ++i) out << arr[i] << " ";
  out << endl;
  return out;
}
template <typename T>
T gcd(T a, T b) {
  T min_v = min(a, b);
  T max_v = max(a, b);
  while (min_v) {
    T temp = max_v % min_v;
    max_v = min_v;
    min_v = temp;
  }
  return max_v;
}
template <typename T>
T lcm(T a, T b) {
  return (a * b) / gcd(a, b);
}
template <typename T>
T fast_exp_pow(T base, T exp, T mod) {
  long long res = 1;
  while (exp) {
    if (exp & 1) {
      res *= base;
      res %= mod;
    }
    exp >>= 1;
    base *= base;
    base %= mod;
  }
  return res % mod;
}
int N, M, K, L, R;
long long C, answer = 99999999999999LL;
long long dp_solve[310][310];
long long min_cost[310][310];
int main() {
  scanf("%d%d%d", &N, &M, &K);
  for (auto i = 0; i < 310; ++i)
    for (auto j = 0; j < 310; ++j)
      dp_solve[i][j] = min_cost[i][j] = 99999999999999LL;
  for (auto i = 0; i < M; ++i) {
    scanf("%d%d%lld", &L, &R, &C);
    min_cost[L][R] = min(min_cost[L][R], C);
  }
  for (auto r = 1; r <= N; ++r)
    for (auto l = 1; l <= r; ++l)
      min_cost[l][r] = min(min_cost[l][r], min_cost[l - 1][r]);
  for (int l = N; l >= 1; --l)
    for (int r = N; r >= l; --r)
      min_cost[l][r] = min(min_cost[l][r], min_cost[l][r + 1]);
  for (auto i = 0; i <= N; ++i) {
    dp_solve[i][0] = 0;
    for (auto j = 0; j <= i; ++j) {
      if (dp_solve[i][j] == 99999999999999LL) continue;
      dp_solve[i + 1][j] = min(dp_solve[i + 1][j], dp_solve[i][j]);
      for (auto k = i + 1; k <= N; ++k)
        dp_solve[k][j + (k - i)] =
            min(dp_solve[k][j + (k - i)], dp_solve[i][j] + min_cost[i + 1][k]);
    }
  }
  answer = dp_solve[N][K];
  if (answer >= 99999999999999LL) answer = -1;
  printf("%lld\n", answer);
  return 0;
}
