import sys from heapq import heappop, heappush input = sys.stdin.buffer.readline INF = 10 ** 18 def main(): def dijkstra(N, G, source, target): dist = [INF] * N que = [(0, source)] dist[source] = 0 while que: c, v = heappop(que) if dist[v] < c: continue for t, cost in G[v]: if dist[v] + cost < dist[t]: dist[t] = dist[v] + cost heappush(que, (dist[t], t)) return dist[target] N, M, K, S, T = map(int, input().split()) S -= 1 T -= 1 passages = tuple(tuple(int(x) - 1 for x in input().split()) for _ in range(M)) node_S = (0, S) node_T = (N - 1, T) node_set = {node_S, node_T} for a, b, c in passages: node_set.add((a, b)) node_set.add((a + 1, c)) node_dict = {t: i for i, t in enumerate(node_set)} L = len(node_set) G = [[] for _ in range(L)] def add_edge(s_bldg, s_floor, t_bldg, t_floor, cost): s = node_dict[(s_bldg, s_floor)] t = node_dict[(t_bldg, t_floor)] G[s].append((t, cost)) for a, b, c in passages: add_edge(a, b, a + 1, c, 0) towers = [[] for _ in range(N)] for a, b in node_set: towers[a].append(b) for i in range(N): towers[i].sort() for j in range(len(towers[i]) - 1): f1 = towers[i][j] f2 = towers[i][j + 1] assert f2 > f1 add_edge(i, f1, i, f2, f2 - f1) add_edge(i, f2, i, f1, f2 - f1) ans = dijkstra(L, G, node_dict[node_S], node_dict[node_T]) print(ans if ans != INF else -1) main()