# coding: utf-8
# Your code here!
from heapq import heappush, heappop
def dijkstra(g,start):
    dist = [1e18]*(len(g)) #startからの最短距離
    dist[start] = 0
    q = [(0,start)] #(そこまでの距離、点)
    pending = len(g)-1 #未確定の点の個数
    while q and pending:
        c,v = heappop(q)
        if dist[v] < c: continue
        pending -= 1
        for to, cost in g[v]:
            if dist[v] + cost < dist[to]:
                dist[to] = dist[v] + cost
                heappush(q, (dist[to], to))
    return dist

import sys
sys.setrecursionlimit(10**6)
readline = sys.stdin.readline #文字列入力のときは注意

n,m,p,q,t = [int(i) for i in readline().split()]
p-=1
q-=1

g = [[] for _ in range(n)]
for i in range(m):
    a,b,c = [int(i) for i in readline().split()]
    g[a-1].append((b-1,c))
    g[b-1].append((a-1,c))

dist0 = dijkstra(g,0)
distp = dijkstra(g,p)
distq = dijkstra(g,q)

ans = -1
for i in range(n):
    for j in range(n):
        m= max(distp[i]+distp[j], distq[i]+distq[j])
        if dist0[i] + dist0[j] + m > t: continue
        ans = max(ans, t-m)

if dist0[p] + distp[q] + dist0[q] <= t: ans = t

print(ans)