#include <bits/stdc++.h>
using namespace std;

struct Edge {
  int ffloor, to, tfloor;
  Edge() {}
  Edge(int ffloor, int to, int tfloor) : ffloor(ffloor), to(to), tfloor(tfloor) {}
};

struct edge {
  int to;
  long long cost;
  edge() {}
  edge(int to, long long cost) : to(to), cost(cost) {}
};

int N, M, K, S, T, a, b, c, cnt;
set<int> st[200001]; // 各棟で使われている階
vector<vector<Edge> > E; // 与えられる辺
vector<vector<edge> > g; // 頑張って作ったグラフ
map<pair<int, int>, int> mp; // {棟の番号, 階数} -> idx
vector<long long> d;

void dijkstra(int s) {
  priority_queue<pair<long long, int>, vector<pair<long long, int> >, greater<pair<long long, int> > > que;
  d.resize(cnt, (long long)(1e18));
  d[s] = 0;
  que.push({0, s});

  while(!que.empty()) {
    pair<long long, int> p = que.top(); que.pop();
    int v = p.second, size_;
    if (d[v] < p.first) continue;
    size_ = g[v].size();
    //cerr << v << endl;
    assert(0 <= v && v < cnt);

    for (int i = 0; i < size_; ++i) {
      edge e = g[v][i];
      if (d[e.to] > d[v] + e.cost) {
        d[e.to] = d[v] + e.cost;
        que.push({d[e.to], e.to});
      }
    }
  }
}

int main() {
  cin.tie(0), cout.tie(0);
  ios::sync_with_stdio(false);

  cin >> N >> M >> K >> S >> T, K--, S--, T--;
  E.resize(N);
  for (int i = 0; i < M; ++i) {
    cin >> a >> b >> c;
    a--, b--, c--;

    st[a].insert(b);
    st[a + 1].insert(c);
    E[a].push_back({b, a + 1, c});
  }
  st[0].insert(S);
  st[N - 1].insert(T);

  int start = -1, goal;
  pair<int, int> prev;

  for (int i = 0; i < N; ++i) {
    prev = {-1, -1};
    for (auto v : st[i]) {
      mp[{i, v}] = cnt++;
      if (prev.first != -1) {
        E[i].push_back({prev.second, i, v});
      }
      prev = {i, v};
    }
  }

  g.resize(cnt);

  for (int i = 0; i < N; ++i) {
    for (auto e : E[i]) {
      g[mp[{i, e.ffloor}]].push_back({mp[{e.to, e.tfloor}], (i == e.to ? abs(e.ffloor - e.tfloor) : 0)});
      if (i == e.to) g[mp[{e.to, e.tfloor}]].push_back({mp[{i, e.ffloor}], (i == e.to ? abs(e.ffloor - e.tfloor) : 0)});
    }
  }

  start = mp[{0, S}];
  goal = mp[{N - 1, T}];
  //cerr << "start is " << start << endl;
  mp.clear();
  E.clear();
  dijkstra(start);
  //cerr << "end\n";
  cout << (d[goal] == (long long)(1e18) ? -1 : d[goal]) << endl;

  //cout << start << " " << goal << endl;

  /*
  for (int i = 0; i < cnt; ++i) {
    for (auto v : g[i]) {
      cerr << i << " " << v.to << " " << v.cost << endl;
    }
  }
  //*/

  return 0;
}