#include <bits/stdc++.h>
using namespace std;
long long cost[305][305], dp[305][305];
class Solution {
 public:
  void solve(std::istream& in, std::ostream& out) {
    int N, M, K;
    in >> N >> M >> K;
    for (int i = 0; i <= 304; i++) {
      for (int j = 0; j <= 304; j++) {
        cost[i][j] = 2e18;
        dp[i][j] = 2e18;
      }
    }
    for (int i = 1; i <= M; i++) {
      int l, r, c;
      in >> l >> r >> c;
      for (int j = l; j <= r; j++) {
        cost[l][j] = min(cost[l][j], (long long)c);
      }
    }
    dp[0][0] = 0;
    for (int i = 1; i <= N; i++) {
      for (int j = 0; j <= K; j++) {
        for (int ii = 0; ii <= i - 1; ii++) dp[i][j] = min(dp[i][j], dp[ii][j]);
        for (int jj = 0; jj <= j; jj++) {
          if (i - jj >= 0 && j - jj >= 0 && i - jj + 1 >= 0)
            dp[i][j] = min(dp[i][j], dp[i - jj][j - jj] + cost[i - jj + 1][i]);
        }
      }
    }
    long long ans = dp[N][K];
    if (ans >= 2e18) ans = -1;
    out << ans << '\n';
    return;
  }
};
void solve(std::istream& in, std::ostream& out) {
  out << std::setprecision(12);
  Solution solution;
  solution.solve(in, out);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  istream& in = cin;
  ostream& out = cout;
  solve(in, out);
  return 0;
}
