#include <iostream>
#include <algorithm>
#include <map>
#include <queue>
using namespace std;
using i64 = long long;

int a, b, c;
map<int, i64> cost[200005];
vector<vector<pair<int, int>>> G;
i64 cc; int p, q;
i64 _cost;
int src, dst;
int k; i64 v;

int main(void) {
  constexpr i64 inf = 987654321987654321LL;
  int N, M, K, S, T; scanf("%d%d%d%d%d", &N, &M, &K, &S, &T);
  --S, --T;
  priority_queue<tuple<i64, int, int>, vector<tuple<i64, int, int>>, greater<tuple<i64, int, int>>> pq;
  pq.emplace(0, 0, S);
  cost[0][S] = 0;
  G.resize(N);
  for(int i=0; i<M; ++i) {
    scanf("%d%d%d", &a, &b, &c);
    --a, --b, --c;
    G[a].emplace_back(b, c);
  }
  while(!pq.empty()) {
    tie(cc, p, q) = pq.top(); pq.pop();
    if(!cost[p].count(q)) { continue; }
    _cost = cost[p][q];
    for(auto&& pr : G[p]) {
      tie(src, dst) = pr;
      if(!cost[p+1].count(dst)) {
        cost[p+1][dst] = _cost + abs(q - src);
        pq.emplace(cost[p+1][dst], p+1, dst);
      }
      else if(cost[p+1][dst] > _cost + abs(q - src)) {
        cost[p+1][dst] = _cost + abs(q - src);
        pq.emplace(cost[p+1][dst], p+1, dst);
      }
    }
  }
  i64 mini = inf;
  for(auto&& kv : cost[N-1]) {
    mini = min(mini, kv.second + abs(T - kv.first));
  }
  if(mini == inf) { mini = -1; }
  printf("%lld\n", mini);
  return 0;
}