<reponame>kagemeka/atcoder-submissions
import sys

import numpy as np
from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import floyd_warshall

n, m = map(int, sys.stdin.readline().split())
I = map(int, sys.stdin.read().split())
abt = list(zip(I, I, I))


def main():
    G = [[0] * n for _ in range(n)]

    for a, b, t in abt:
        G[a - 1][b - 1] = t
        G[b - 1][a - 1] = t

    dist = floyd_warshall(csgraph=csr_matrix(G), directed=False)

    ans = np.amin(np.amax(dist, axis=1))
    print(ans)


if __name__ == "__main__":
    main()
