#include <bits/stdc++.h>
using namespace std;
const int INF = 2147483647;
const int MAXN = 1000;
const int MAXM = 100000;
int n, m;
// 正图 0、反图 1，实际上 [2][MAXN+5] 可能会更快一点
vector<pair<int, int>> e[MAXN + 5][2];
int dis[MAXN + 5][2];
bool vis[MAXN + 5];
priority_queue<pair<int, int>> pq;
void dijkstra(int s, int typ)
{
    for (int i = 1; i <= n; i++)
    {
        dis[i][typ] = INF;
        vis[i] = false;
    }
    dis[s][typ] = 0;
    pq.push({-0, s});
    while (!pq.empty())
    {
        int u = pq.top().second;
        pq.pop();
        if (vis[u])
            continue;
        vis[u] = true;
        for (int i = 0; i < e[u][typ].size(); i++)
        {
            int v = e[u][typ][i].first;
            int w = e[u][typ][i].second;
            if (dis[u][typ] + w < dis[v][typ])
            {
                dis[v][typ] = dis[u][typ] + w;
                pq.push({-dis[v][typ], v});
            }
        }
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= m; i++)
    {
        int u, v, w;
        cin >> u >> v >> w;
        e[u][0].push_back({v, w});
        e[v][1].push_back({u, w});
    }
    dijkstra(1, 0);
    dijkstra(1, 1);
    int ans = 0;
    for (int i = 2; i <= n; i++)
        ans += dis[i][0] + dis[i][1];
    cout << ans;
    return 0;
}