#include <bits/stdc++.h>
using namespace std;
int n, m, k;
long long d[305][305];
long long dp[305][305];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m >> k;
  for (int i = 1; i <= n; ++i)
    for (int j = i; j <= n; ++j) d[i][j] = 1e15;
  for (int i = 1; i <= m; ++i) {
    int x, y;
    long long z;
    cin >> x >> y >> z;
    for (int j = x; j <= y; ++j) d[j][y] = min(d[j][y], z);
  }
  for (int i = 0; i <= n; ++i)
    for (int j = 1; j <= n; ++j) dp[i][j] = 1e15;
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= i; ++j) {
      dp[i][j] = dp[i - 1][j];
      for (int k = i - 1; k >= 0 && i - k <= j; --k)
        dp[i][j] = min(dp[i][j], dp[k][j - i + k] + d[k + 1][i]);
    }
  }
  cout << (dp[n][k] == 1e15 ? -1 : dp[n][k]);
}
