#rosalind_ba5d

import networkx as nx

#read data

f = open('rosalind_ba5d.txt')

s = int(f.readline().rstrip())

t = int(f.readline().rstrip())

G = nx.DiGraph()

for line in f:

l = line.rstrip().split('->')

u = int(l[0])

v, w = map(int, l[1].split(':'))

# sign-reverse weight, thus turn a longest path problem to

# a shortest path search with bellman_ford

G.add_edge(u, v, weight=-w)

bf = nx.bellman_ford(G, s)

longest = -bf[1][t]

path = []

while t != None:

path.append(t)

t = bf[0][t]

path = path[::-1]

'''

longest = 0

path = []

for p in nx.all_simple_paths(G, s, t):

len_p = 0

for i in range(len(p) - 1):

len_p += G[p[i]][p[i+1]]['weight']

if len_p > longest:

longest = len_p

path = p

'''

print(longest)

print(path)

open('rosalind_ba5d_sub.txt', 'wt').write(str(longest)+'\n'+'->'.join(map(str,path)))