#include <bits/stdc++.h>
using namespace std;
long long mincost[301][301];
long long dp[301][301];
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  for (int i = 0; i < 301; i++) {
    for (int j = 0; j < 301; j++) {
      dp[i][j] = mincost[i][j] = 400000000000;
    }
  }
  for (int i = 0; i < m; i++) {
    int l, r;
    long long c;
    cin >> l >> r >> c;
    mincost[l][r] = min(mincost[l][r], c);
  }
  for (int i = 1; i < 301; i++) {
    for (int j = 0; j < 301; j++) {
      mincost[i][j] = min(mincost[i][j], mincost[i - 1][j]);
    }
  }
  for (int i = 0; i < 301; i++) {
    dp[i][0] = 0;
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j <= n; j++) {
      dp[i][j] = min(dp[i][j], dp[i - 1][j]);
      for (int k = 0; k < i; k++) {
        dp[i][j] =
            min(dp[i][j], dp[k][max(0, j - (i - k))] + mincost[k + 1][i]);
      }
    }
  }
  long long ans = 400000000000;
  ans = min(ans, dp[n][k]);
  if (ans >= 400000000000) {
    cout << -1 << endl;
  } else {
    cout << ans << endl;
  }
}
