from heapq import heappush,heappop

n,m,p,q,t = map(int,input().split())
e = [[] for i in range(n)]
for _ in range(m):
    a,b,c = map(int,input().split())
    a,b = a-1,b-1
    e[a].append([b,c])
    e[b].append([a,c])

p,q = p-1,q-1

inf = 10**20
mod = 1<<16
def dijkstra(x):
    dis = [inf]*n
    dis[x] = 0
    h = [x]
    while h:
        d,now = divmod(heappop(h),mod)
        if dis[now] != d:
            continue
        for nex,c in e[now]:
            if dis[nex] > d+c:
                dis[nex] = d+c
                heappush(h,((d+c)<<16)+nex)
    return dis


dis0 = dijkstra(0)
disp = dijkstra(p)
disq = dijkstra(q)
ans = -1

if dis0[p]+dis0[q]+disp[q] <= t:
    print(t)
    exit()
    
for i in range(n):
    for j in range(n):
        t1 = dis0[i]
        t2 = dis0[j]
        
        t3 = max(disp[i]+disp[j],disq[i]+disq[j])

        if t1+t2+t3 > t:
            continue
        ans = max(ans,t-t3)
if ans == inf:
    ans = -1
print(ans)