import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = 10**16
# md = 998244353
md = 10**9+7

from heapq import *

n,m,p,q,t=LI()
p,q=p-1,q-1
to=[[] for _ in range(n)]
for _ in range(m):
    u,v,c=LI()
    u,v=u-1,v-1
    to[u].append((v,c))
    to[v].append((u,c))

def dijkstra(u):
    dist=[inf]*n
    dist[u]=0
    hp=[(0,u)]
    while hp:
        d,u=heappop(hp)
        if d>dist[u]:continue
        for v,c in to[u]:
            nd=d+c
            if nd>=dist[v]:continue
            dist[v]=nd
            heappush(hp,(nd,v))
    return dist

to0=dijkstra(0)
top=dijkstra(p)
toq=dijkstra(q)

if to0[p]+to0[q]+top[q]<=t:
    print(t)
    exit()

ans=inf
for u in range(n):
    mx=max(top[u],toq[u])
    if (to0[u]+mx)*2>t:continue
    ans=min(ans,mx)

if ans==inf:ans=-1
else:ans=t-ans*2
print(ans)