#include <bits/stdc++.h>
using namespace std;
const long long int mod = 1e9 + 7;
const long long int inf = 2e18 + 5;
double PI = 3.14159265358979323846;
const int N = 305;
long long int dp[N][N];
long long int cost[N][N];
void solve() {
  int n, m, k;
  cin >> n >> m >> k;
  fill(cost[0], cost[n + 1], inf);
  fill(dp[0], dp[n + 1], inf);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      dp[i][j] = inf;
    }
  }
  long long int l, r, c;
  for (int i = 0; i < m; i++) {
    cin >> l >> r >> c;
    for (int j = l; j <= r; j++) {
      cost[j][r] = min(cost[j][r], c);
    }
  }
  for (int i = 0; i <= n; i++) {
    dp[i][0] = 0;
    for (int j = 1; j <= i; j++) {
      dp[i][j] = min(dp[i][j], dp[i - 1][j]);
      long long int cur = inf;
      for (int l = 1; l <= j; l++) {
        cur = min(cur, dp[i - l][j - l]);
        if (cost[i - l + 1][i] == inf or cur == inf) continue;
        dp[i][j] = min(dp[i][j], cur + cost[i - l + 1][i]);
      }
    }
  }
  long long int ans = dp[n][k];
  if (ans == inf) ans = -1;
  cout << ans << "\n";
}
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
