#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N, M;
    cin >> N >> M;

    vector<vector<int>> g(N);
    vector<long long> D(N);

    for (int i = 0; i < M; ++i) {
        int u, v;
        long long w;
        cin >> u >> v >> w;
        u--, v--;

        g[u].push_back(v);
        g[v].push_back(u);

        D[u] += w;
        D[v] += w;
    }

    vector<int> used(N);
    long long ans2 = 0;

    for (int s = 0; s < N; ++s) {
        if (used[s]) continue;

        vector<int> comp;
        queue<int> q;

        q.push(s);
        used[s] = 1;

        while (!q.empty()) {
            int v = q.front();
            q.pop();

            comp.push_back(v);

            for (int to : g[v]) {
                if (used[to]) continue;
                used[to] = 1;
                q.push(to);
            }
        }

        vector<long long> a;
        for (int v : comp) a.push_back(D[v]);

        sort(a.begin(), a.end(), greater<>());

        for (int i = 0; i < (int)a.size(); ++i) {
            if (i % 2 == 0) ans2 += a[i];
            else ans2 -= a[i];
        }
    }

    cout << ans2 / 2 << '\n';
}