import heapq
import sys
n, m, p, q, t=map(int, input().split())
p-=1
q-=1
g=[[] for i in range(n)]
for i in range(m):
  a, b, c=map(int, input().split())
  a-=1
  b-=1
  g[a].append((c, b))
  g[b].append((c, a))
def dijkstra(s):
  d=[10**18]*n
  d[s]=0
  que=[]
  heapq.heappush(que, (0, s))
  while len(que)!=0:
    u=heapq.heappop(que)
    x=u[1]
    if d[x]<u[0]:
      continue
    for v in g[x]:
      y=v[1]
      if d[y]>d[x]+v[0]:
        d[y]=d[x]+v[0]
        heapq.heappush(que, (d[y], y))
  return d
d1=dijkstra(0)
dp=dijkstra(p)
dq=dijkstra(q)
if d1[p]+dp[q]+d1[q]<=t:
  print(t)
  sys.exit()
elif max(d1[p]*2, d1[q]*2)>t:
  print(-1)
  sys.exit()
ans=0
for i in range(n):
  for j in range(n):
    if d1[i]+max(dp[i]+dp[j], dq[i]+dq[j])+d1[j]<=t:
      ans=max(ans, t-max(dp[i]+dp[j], dq[i]+dq[j]))
print(ans)