import sys
import numpy as np
from scipy.sparse.csgraph import dijkstra
from scipy.sparse import csr_matrix

input = sys.stdin.buffer.readline

N, M, P, Q, T = map(int, input().split())
P -= 1
Q -= 1
edges = np.array([tuple(map(int, input().split())) for _ in range(M)]).T

matr = csr_matrix((edges[2], (edges[:2] - 1)), shape=(N, N))
way_1, way_p, way_q = dijkstra(matr, indices=(0, P, Q), directed=False).astype(int)

if way_1[P] + way_1[Q] + way_p[Q] <= T:
    print(T)
    exit()

xpy = way_p[:, None] + way_p[None, :]
xqy = way_q[:, None] + way_q[None, :]
xy1 = way_1[:, None] + way_1[None, :]
res = np.where((xy1 + xpy <= T) & (xy1 + xqy <= T), T - np.maximum(xpy, xqy), -1)
ans = res.max()
print(ans)