from collections import defaultdict

import heapq
INF = float('inf')
def dijkstra(s, edge):
    dist = defaultdict(lambda: INF)
    dist[s] = 0
    edgelist = []
    heapq.heappush(edgelist,(dist[s], s))
    while edgelist:
        minedge = heapq.heappop(edgelist)
        if dist[minedge[1]] < minedge[0]:
            continue
        v = minedge[1]
        for e in edge[v]:
            if dist[e[1]] > dist[v]+e[0]:
                dist[e[1]] = dist[v]+e[0]
                heapq.heappush(edgelist,(dist[e[1]], e[1]))
    return dist

import sys
import io, os
input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline

def main():

    n,m,k,s,t = map(int, input().split())
    s,t = s-1, t-1
    edge = defaultdict(lambda: [])
    V = [[] for i in range(n)]
    V[0].append(0)
    V[n-1].append(t)
    for i in range(m):
        a, b, c = map(int, input().split())
        a, b, c = a-1, b-1, c-1
        edge[b*n+a].append((0, c*n+a+1))
        V[a].append(b)
        V[a+1].append(c)

    for a, l in enumerate(V):
        l.sort()
        for i in range(len(l)-1):
            x, y = l[i], l[i+1]
            d = abs(x-y)
            edge[x*n+a].append((d, y*n+a))
            edge[y*n+a].append((d, x*n+a))

    t = t*n+n-1
    D = dijkstra(s, edge)
    if D[t] < INF:
        print(D[t])
    else:
        print(-1)

if __name__ == '__main__':
    main()