import heapq

INF = 1 << 60

n, m, k, s, t = map(int, input().split())
s -= 1
t -= 1

idx = {}
idx.setdefault(s, len(idx))
idx.setdefault((n - 1) * k + t, len(idx))

adj = [set([0, k - 1]) for _ in range(n)]
for b in range(n):
  idx.setdefault(b * k, len(idx))
  idx.setdefault(b * k + k - 1, len(idx))

adj[0].add(s)
adj[n - 1].add(t)

arcs = []
for _ in range(m):
  a, b, c = map(int, input().split())
  a -= 1
  b -= 1
  c -= 1

  x = a * k + b
  y = (a + 1) * k + c
  idx.setdefault(x, len(idx))
  idx.setdefault(y, len(idx))
  arcs.append((idx[x], idx[y]))

  adj[a].add(b)
  adj[a + 1].add(c)

g = [[] for _ in range(len(idx))]
for u, v in arcs:
  g[u].append((v, 0))

for b in range(n):
  floors = sorted(list(adj[b]))
  for i in range(len(floors) - 1):
    x = b * k + floors[i]
    y = b * k + floors[i + 1]
    cost = floors[i + 1] - floors[i]
    g[idx[x]].append((idx[y], cost))
    g[idx[y]].append((idx[x], cost))

dist = [INF for _ in range(len(idx))]
src = idx[s]
dst = idx[(n - 1) * k + t]
dist[src] = 0
hp = [(dist[src], src)]
while len(hp) > 0:
  cd, cur = heapq.heappop(hp)
  if cd > dist[cur]:
    continue
  for nxt, cost in g[cur]:
    if dist[cur] + cost < dist[nxt]:
      dist[nxt] = dist[cur] + cost
      heapq.heappush(hp, (dist[nxt], nxt))

if dist[dst] < INF:
  print(dist[dst])
else:
	print("-1")