#include <bits/stdc++.h>
using namespace std;
int m, n, k;
long long f[310][310], s[310][310];
int l[100100], r[100100];
long long c[100100];
long long ans;
int i, j, p;
int main() {
  cin >> n >> m >> k;
  memset(f, -1, sizeof(f));
  memset(s, 1000000000000005, sizeof(s));
  for (i = 1; i <= m; i++) {
    cin >> l[i] >> r[i] >> c[i];
    for (j = l[i]; j <= r[i]; j++)
      if (c[i] < s[j][r[i]]) s[j][r[i]] = c[i];
  }
  for (i = 0; i <= n; i++)
    for (j = 0; j <= n; j++) f[i][j] = 1000000000000005;
  f[0][0] = 0;
  for (i = 0; i <= n; i++)
    for (j = 0; j <= i; j++)
      if (f[i][j] < 1000000000000005) {
        f[i + 1][j] = min(f[i + 1][j], f[i][j]);
        for (p = i + 1; p <= n; p++)
          if (s[i + 1][p] != -1)
            f[p][j + p - i] = min(f[p][j + p - i], f[i][j] + s[i + 1][p]);
      }
  ans = 1000000000000005;
  for (j = k; j <= n; j++)
    if (f[n][j] < ans) ans = f[n][j];
  if (ans == 1000000000000005)
    cout << "-1" << endl;
  else
    cout << ans << endl;
  return 0;
}
