#include <bits/stdc++.h>
using namespace std;
const int mod = 998244353;
void solve() {
  long long n, m, k;
  cin >> n >> m >> k;
  long long cost[310][310], dp[310][310];
  for (int i = 0; i <= 300; ++i) {
    for (int j = 0; j <= 300; ++j) {
      dp[i][j] = 1000000000000000;
      cost[i][j] = 1000000000000000;
    }
  }
  for (int i = 0; i <= n; ++i) dp[i][0] = 0;
  long long l, r, c;
  for (int i = 0; i < m; ++i) {
    cin >> l >> r >> c;
    for (int j = l; j <= r; ++j) cost[l][j] = min(cost[l][j], c);
  }
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= i; ++j) {
      dp[i][j] = dp[i - 1][j];
      for (int p = 1; p <= j; ++p)
        dp[i][j] = min(dp[i][j], dp[i - p][j - p] + cost[i - p + 1][i]);
    }
  }
  long long ans = pow(10, 18);
  for (int i = 1; i <= n; ++i)
    for (int j = k; j <= n; ++j) ans = min(ans, dp[i][j]);
  if (ans > pow(10, 14)) ans = -1;
  cout << ans;
}
int main() { solve(); }
