#include <bits/stdc++.h>
using namespace std;
const int MaxN = 305;
const long long oo = 1000000000000000ll;
const long long Base = 1000000007;
typedef int Tarr[MaxN];
int n, m, K;
long long f[MaxN][MaxN], g[MaxN][MaxN];
int main() {
  cin >> n >> m >> K;
  for (int i = 0; i <= n; i++)
    for (int j = 0; j <= n; j++) {
      f[i][j] = oo;
      g[i][j] = oo;
    }
  for (int i = 1; i <= m; i++) {
    int l, r, c;
    cin >> l >> r >> c;
    for (int j = l; j <= r; j++)
      for (int k = j; k <= r; k++) f[j][k] = min(f[j][k], (long long)c);
  }
  for (int l = 1; l <= n; l++)
    for (int i = 1; i <= n - l + 1; i++) {
      int j = i + l - 1;
      for (int k = i + 1; k <= j; k++)
        f[i][j] = min(f[i][j], f[i][k - 1] + f[k][j]);
    }
  for (int i = 0; i <= n; i++) g[i][0] = 0;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= K; j++) {
      g[i][j] = g[i - 1][j];
      for (int k = i; k >= 1; k--)
        if (j >= (i - k + 1))
          g[i][j] = min(g[i][j], g[k - 1][j - (i - k + 1)] + f[k][i]);
    }
  if (g[n][K] >= oo)
    cout << "-1";
  else
    cout << g[n][K];
  return 0;
}
