#include <bits/stdc++.h>

using namespace std;
const long long INF = 1LL<<60;

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int n, v, l;
  cin >> n >> v >> l;

  vector<int> x(n+2), y(n+2), c(n+2);
  x[n+1] = l;
  for (int i = 1; i <= n; i++)
    cin >> x[i] >> y[i] >> c[i];

  vector<vector<long long> > dp(n+2, vector<long long>(v+1));
  for (int i = 0; i < v; i++) dp[0][i] = INF;

  for (int i = 1; i <= n+1; i++) {
    queue<long long> q;
    multiset<long long> s;
    for (int j = 0; j <= v; j++) {
      // 給油する
      long long v1 = s.size() ? (*s.begin() + c[i]) : INF;

      // 給油しない
      int d = x[i] - x[i-1];
      long long v2 = (j + d) <= v ? dp[i-1][j+d] : INF;

      dp[i][j] = min(v1, v2);
      
      q.push(v2);
      s.insert(v2);

      if (q.size() > min(v, y[i])) {
        s.erase(s.find(q.front()));
        q.pop();
      }
    }
  }

  long long ret = INF;
  for (int i = 0; i <= v; i++)
    ret = min(ret, dp[n+1][i]);

  if (ret == INF)
    ret = -1;
  cout << ret << endl;
  
  return 0;
}