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

struct Edge {
    int u, v;
    long long w;
};

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

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

    vector<Edge> edges(M);
    vector<vector<long long>> ws(N);

    for (auto &[u, v, w] : edges) {
        cin >> u >> v >> w;
        u--, v--;

        ws[u].push_back(w);
        ws[v].push_back(w);
    }

    vector<long long> first(N), second(N);

    for (int v = 0; v < N; ++v) {
        sort(ws[v].begin(), ws[v].end(), greater<>());

        if (ws[v].size() >= 1) first[v] = ws[v][0];
        if (ws[v].size() >= 2) second[v] = ws[v][1];
    }

    vector<int> ord(N);
    iota(ord.begin(), ord.end(), 0);

    sort(ord.begin(), ord.end(), [&](int a, int b) {
        if (second[a] != second[b]) return second[a] > second[b];
        if (first[a] != first[b]) return first[a] > first[b];
        return a < b;
    });

    vector<int> owner(N);

    for (int i = 0; i < N; ++i) {
        owner[ord[i]] = i % 2;
    }

    long long ans = 0;

    for (auto [u, v, w] : edges) {
        if (owner[u] != owner[v]) continue;

        if (owner[u] == 0) ans += w;
        else ans -= w;
    }

    cout << ans << '\n';
}