from collections import defaultdict
import sys
sys.setrecursionlimit(10**6)

def dfs(i, oi=-1, d=0):
    if len(to[i]) == 1:
        if to[i][0][0] == oi:
            return d
    mx = 0
    for ki, kd in to[i]:
        if ki == oi: continue
        tmp = dfs(ki, i, d + kd)
        if tmp > mx:
            mx = tmp
    return mx

n, m = map(int, input().split())
to = defaultdict(list)
for _ in range(m):
    a, b, c = map(int, input().split())
    a -= 1
    b -= 1
    to[a].append([b, c])
    to[b].append([a, c])
print(max(dfs(i) for i in range(n)))