#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int maxn = 1e6 + 5;
long long int power(long long int base, long long int exp) {
  long long int res = 1;
  while (exp) {
    if (exp % 2) res *= base;
    base *= base;
    res %= mod;
    base %= mod;
    exp /= 2;
  }
  return res;
}
long long int n, m, k, l[maxn], r[maxn], dp[350][350], adj[350][350], c[maxn];
long long int go(long long int idx, long long int k) {
  if (k <= 0) return 0;
  if (idx >= n + 1) return 1e16;
  long long int &ret = dp[idx][k];
  if (ret != -1) return ret;
  ret = go(idx + 1, k);
  for (long long int i = idx; i <= min(idx + k, n); i++) {
    ret = min(ret, go(i + 1, k - (i - idx + 1)) + adj[idx][i]);
  }
  return ret;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> m >> k;
  for (long long int i = 1; i <= n; i++)
    for (long long int j = i; j <= n; j++) adj[i][j] = 1e15;
  for (long long int i = 1; i <= m; i++) {
    cin >> l[i] >> r[i] >> c[i];
    adj[l[i]][r[i]] = min(adj[l[i]][r[i]], c[i]);
  }
  for (long long int i = 1; i <= n; i++) {
    for (long long int j = 1; j <= n; j++) {
      if (i < j) break;
      for (long long int k = j; k <= n; k++) {
        adj[j][k] = min(adj[j][k], adj[j][i] + adj[i][k]);
      }
    }
  }
  memset(dp, -1, sizeof(dp));
  long long int ans = go(1, k);
  if (ans > 1e12) ans = -1;
  cout << ans;
  return 0;
}
