from heapq import *

n, m, p, q, t = map(int, input().split())
p -= 1
q -= 1
edges = [[] for _ in range(n)]
for _ in range(m):
    u, v, c = map(int, input().split())
    u -= 1
    v -= 1
    edges[u].append((v, c))
    edges[v].append((u, c))

def dijkstra(s):
    inf = 1 << 60
    dist = [inf] * n
    dist[s] = 0
    hq = [s]
    while hq:
        tmp = heappop(hq)
        d = tmp // n
        pos = tmp - d * n
        if dist[pos] < d:
            continue
        for npos, c in edges[pos]:
            tmp = c + d
            if dist[npos] > tmp:
                dist[npos] = tmp
                heappush(hq, (tmp * n + npos))
    return dist

d0 = dijkstra(0)
dp = dijkstra(p)
dq = dijkstra(q)

if d0[p] + dp[q] + dq[0] <= t:
    print(t)
elif max(d0[p] * 2, d0[q] * 2) > t:
    print(-1)
else:
    ans = 0
    for i in range(n):
        for j in range(n):
            d = d0[i] + d0[j]
            d1 = max(dp[i] + dp[j], dq[i] + dq[j])
            if d + d1 <= t:
                ans = max(ans, t - d1)
    print(ans)