#include <iostream>

using namespace std;

long long dist[250][250];

int main()
{
    int C, F;
    cin >> C >> F;

    for(int i = 1; i <= C; i++)
    {
        for(int j = 1; j <= C; j++)
        {
            dist[i][j] = 1000000000000000LL; //set all to infinity initially
        }
        dist[i][i] = 0; //distance to self is zero
    }

    for(int i = 0; i < F; i++)
    {
        int u, v, p;
        cin >> u >> v >> p;
        dist[u][v] = dist[v][u] = p;
        //if an edge exists between u,v then initial dist between them
        //is set to the weight of the edge
    }

    //Floyd-Warshall Algorithm
    for(int k = 1; k <= C; k++)
    {
        for(int i = 1; i <= C; i++)
        {
            for(int j = 1; j <= C; j++)
            {
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
            }
        }
    }

    long long int ans = 0;
    for(int i = 1; i <= C; i++)
    {
        for(int j = 1; j <= C; j++)
        {
            if(dist[i][j] != 1000000000000000LL) ans = max(ans, dist[i][j]);
            //finding maximum of all non-infinity distances
        }
    }

    cout << ans;
}