#include <bits/stdc++.h>
using namespace std;
int gint() {
  char c;
  int f = 1;
  while (c = getchar(), c < 48 || c > 57)
    if (c == '-') f = -1;
  int x = 0;
  for (; c > 47 && c < 58; c = getchar()) {
    x = x * 10 + c - 48;
  }
  return x * f;
}
int n, m, k;
long long f[305][305], cost[305][305];
int main() {
  n = gint(), m = gint(), k = gint();
  for (int i = 1; i <= n; ++i)
    for (int j = 1; j <= n; ++j) cost[i][j] = 1ll << 40;
  for (int i = 1, l, r, c; i <= m; ++i) {
    l = gint(), r = gint(), c = gint();
    for (int j = l; j <= r; ++j) cost[l][j] = min(cost[l][j], 1ll * c);
  }
  for (int i = 0; i <= n; ++i)
    for (int j = 0; j <= n; ++j) f[i][j] = 1ll << 40;
  f[0][0] = 0;
  for (int i = 1; i <= n; ++i) {
    f[i][0] = 0;
    for (int j = 1; j <= i; ++j) {
      f[i][j] = f[i - 1][j];
      for (int k = 1; k <= j; ++k) {
        f[i][j] = min(f[i][j], f[i - k][j - k] + cost[i - k + 1][i]);
      }
    }
  }
  if (f[n][k] == 1ll << 40)
    puts("-1");
  else
    printf("%I64d\n", f[n][k]);
  return 0;
}
