MOD = 10 ** 9 + 7
INF = 10 ** 12
import sys
sys.setrecursionlimit(100000000)
dy = (-1,0,1,0)
dx = (0,1,0,-1)
from  itertools import permutations
from heapq import heapify,heappop,heappush

def dijkstra(G,s = 0): #sを始点とした最短経を求める
    n = len(G)
    dist = [INF] * n
    dist[s] = 0

    q = [(0,s)]
    heapify(q)

    while q:
        d,v = heappop(q)
        if dist[v] < d:
            continue
        for e,cost in G[v]:
            if dist[e] > dist[v] + cost:
                dist[e] = dist[v] + cost
                heappush(q,(dist[e],e))
    
    return dist

def main():
    n,m,p,q,t = map(int,input().split())
    p -= 1
    q -= 1
    G = [[] for _ in range(n)]
    for _ in range(m):
        a,b,c = map(int,input().split())
        a -= 1
        b -= 1
        G[a].append((b,c))
        G[b].append((a,c))
    
    d0 = dijkstra(G)
    dp = dijkstra(G,p)
    dq = dijkstra(G,q)
    if d0[p] + dp[q] + dq[0] <= t:
        print(t)
        return

    ans = -1
    for i in range(n):
        if 2 * (d0[i] + dp[i] + dq[i]) <= t:
            print(t)
            return
        if 2 * (max(dp[i],dq[i]) + d0[i]) <= t:
            ans = max(ans,t - 2 * max(dp[i],dq[i]))
    print(ans)

if __name__ =='__main__':
    main()