#include <bits/stdc++.h>

using namespace std;

#define int long long
#define FOR(i, a, b) for(ll i = (a); i < (b); ++i)
#define FORR(i, a, b) for(ll i = (a); i > (b); --i)
#define REP(i, n) for(ll i = 0; i < (n); ++i)
#define REPR(i, n) for(ll i = n; i >= 0; i--)
#define FOREACH(x, a) for(auto &(x) : (a))
#define VECCIN(x)                                                              \
    for(auto &youso_ : (x)) cin >> youso_
#define bitcnt __builtin_popcount
#define SZ(x) ((ll)(x).size())
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
template <typename T = long long> inline T IN() {
    T x;
    cin >> x;
    return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&... tail) {
    cin >> head;
    CIN(move(tail)...);
}
#define CINT(...)                                                              \
    int __VA_ARGS__;                                                           \
    CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
    double __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
    ll __VA_ARGS__;                                                            \
    CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
    string __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define Yes(a) cout << (a ? "Yes" : "No") << "\n"
#define YES(a) cout << (a ? "YES" : "NO") << "\n"
#define Printv(v)                                                              \
    {                                                                          \
        FOREACH(x, v) { cout << x << " "; }                                    \
        cout << "\n";                                                          \
    }
template <typename T = string> inline void eputs(T s) {
    cout << s << "\n";
    exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
    std::fill((T *)array, (T *)(array + N), val);
}
template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef unsigned long long ul;
typedef vector<ll> VL;
typedef pair<ll, ll> PL;

const int INF = 1e9;
const int MOD = 1e9 + 7;
const double PI = atan(1.0) * 4.0;
// const int MOD = 998244353;
const ll LINF = 1e18;
const ll dx[] = {1, 0, -1, 0};
const ll dy[] = {0, 1, 0, -1};

void cinfast() {
    cin.tie(0);
    ios::sync_with_stdio(false);
}
class MinimumCostFlow {
    struct Edge {
        const unsigned int to;  // 行き先のノードid
        long long flow;         // 流量
        const long long cap;    // 容量
        const long long cost;   // コスト
        const unsigned int rev; // 逆辺のノードid
        const bool is_rev;      // 逆辺かどうか
        Edge(unsigned int to, long long flow, long long cap, long long cost,
             unsigned int rev, bool is_rev)
            : to(to), flow(flow), cost(cost), cap(cap), rev(rev),
              is_rev(is_rev) {
            assert(this->cap >= 0);
        }
    };

    const int num_node;                   // 頂点数
    std::vector<std::vector<Edge>> graph; // グラフの隣接リスト表現
    bool have_negative_cost = false;      // 負辺があるか

  public:
    MinimumCostFlow(int num_node) : num_node(num_node) {
        graph.resize(num_node);
    }

    // fromからtoへ向かう容量cap、コストcostの辺をグラフに追加する
    void add_edge(unsigned int from, unsigned int to, long long cap,
                  long long cost) {
        graph.at(from).emplace_back(
            Edge(to, 0, cap, cost, graph.at(to).size(), false));
        graph.at(to).emplace_back(
            Edge(from, cap, cap, -cost, graph.at(from).size() - 1, true));
        have_negative_cost |= cost < 0;
    }

    // sからtへの流量fの最小費用流を求める
    // 流せない場合は-1を返す
    bool run(const unsigned int source, const unsigned int sink,
             long long flow) {

        // 負閉路がある場合、先に負閉路にそって流しておく
        // 負辺があっても負閉路ない場合はこの処理をskipしていい
        if(have_negative_cost) {
            remove_negative_cycles(source);
        }

        std::vector<int> prev_v(num_node, -1),
            prev_e(num_node, -1); // 直前の頂点と辺のidx
        std::vector<long long> potential(num_node, 0); // ポテンシャル

        // 負の辺がある場合、ポテンシャルをベルマンフォードで求めておく
        // 負の辺がない場合はこの処理をskipしていい
        if(have_negative_cost) {
            potential.assign(num_node, INT_MAX);
            potential.at(source) = 0;
            while(true) {
                bool updated = false;
                for(int v = 0; v < num_node; ++v) {
                    for(auto &e : graph.at(v)) {
                        if(e.cap - e.flow > 0) {
                            if(potential.at(v) == INT_MAX) {
                                continue;
                            }
                            if(potential.at(e.to) > potential.at(v) + e.cost) {
                                potential.at(e.to) = potential.at(v) + e.cost;
                                updated = true;
                            }
                        }
                    }
                }
                if(not updated) {
                    break;
                }
            }
        }

        while(flow > 0) {
            // ダイクストラ法を用いてポテンシャルを更新する
            std::priority_queue<std::pair<int, int>,
                                std::vector<std::pair<int, int>>,
                                std::greater<std::pair<int, int>>>
                que;
            std::vector<long long> distance(num_node,
                                            LINF); // 最短距離

            distance.at(source) = 0;
            que.push(std::make_pair(0, source));
            while(not que.empty()) {
                std::pair<int, int> p =
                    que.top(); // firstは最短距離、secondは頂点の番号
                que.pop();
                int v = p.second;
                if(distance.at(v) < p.first) {
                    continue;
                }
                for(int i = 0; i < graph.at(v).size(); ++i) {
                    Edge &e = graph.at(v).at(i);
                    if(e.cap - e.flow > 0 and
                       distance.at(e.to) > distance.at(v) + e.cost +
                                               potential.at(v) -
                                               potential.at(e.to)) {
                        distance.at(e.to) = distance.at(v) + e.cost +
                                            potential.at(v) -
                                            potential.at(e.to);
                        prev_v.at(e.to) = v;
                        prev_e.at(e.to) = i;
                        que.push(std::make_pair(distance.at(e.to), e.to));
                    }
                }
            }

            // これ以上流せない
            if(distance[sink] == LINF) {
                return false;
            }
            for(int v = 0; v < num_node; ++v) {
                potential.at(v) += distance.at(v);
            }

            // source-sink間で流せる量を求める
            long long d = flow;
            for(int v = sink; v != source; v = prev_v.at(v)) {
                auto &e = graph.at(prev_v.at(v)).at(prev_e.at(v));
                d = std::min(d, e.cap - e.flow);
            }

            flow -= d;
            for(int v = sink; v != source; v = prev_v.at(v)) {
                Edge &e = graph.at(prev_v.at(v)).at(prev_e.at(v));
                e.flow += d;
                graph.at(v).at(e.rev).flow -= d;
            }
        }
        return true;
    }

    // 最小費用を取得する
    int min_cost_flow() {
        int cost = 0;
        for(int u = 0; u < graph.size(); ++u) {
            for(int i = 0; i < graph.at(u).size(); ++i) {
                Edge &e = graph.at(u).at(i);
                if(not e.is_rev) {
                    cost += e.flow * e.cost;
                }
            }
        }
        return cost;
    }

  private:
    // 負閉路を除去する
    void remove_negative_cycles(const unsigned int source) {
        while(true) {
            // bellman-fordでsourceからの最短路を求める
            std::vector<int> prev_v(num_node, -1),
                prev_e(num_node, -1); // 直前の頂点と辺のidx
            std::vector<long long> distance(num_node, LINF);
            distance.at(source) = 0;

            int negative_cycle_idx = -1;
            for(int num = 0; num < num_node; ++num) {
                for(int u = 0; u < graph.size(); ++u) {
                    for(int i = 0; i < graph.at(u).size(); ++i) {
                        Edge &e = graph.at(u).at(i);

                        if(distance.at(u) == LINF) {
                            continue;
                        }

                        long long new_dist = distance.at(u) + e.cost;
                        if(e.cap - e.flow > 0 and
                           distance.at(e.to) > new_dist) {
                            distance.at(e.to) = new_dist;
                            prev_v.at(e.to) = u;
                            prev_e.at(e.to) = i;

                            if(num == num_node - 1) {
                                negative_cycle_idx = e.to;
                            }
                        }
                    }
                }
            }

            // 負閉路がない
            if(negative_cycle_idx == -1) {
                return;
            }

            long long d = LINF;
            std::vector<bool> used(num_node, false);
            int u = negative_cycle_idx;
            while(not used.at(u)) {
                used.at(u) = true;
                const Edge &e = graph.at(prev_v.at(u)).at(prev_e.at(u));
                d = std::min(d, e.cap - e.flow);
                u = prev_v.at(u);
            }

            assert(d != 0);

            std::fill(used.begin(), used.end(), false);
            // 閉路の開始点から見ていく
            while(not used.at(u)) {
                used.at(u) = true;
                Edge &e = graph.at(prev_v.at(u)).at(prev_e.at(u));
                e.flow += d;
                graph.at(e.to).at(e.rev).flow -= d;
                u = prev_v.at(u);
            }
        }
    }
};

using VVL = vector<VL>;

signed main() {
    LCIN(N, M);
    VVL G(N, VL(N, LINF));
    REP(i, N) G[i][i] = 0;
    MinimumCostFlow mcf(N + 2);
    ll s = N, t = s + 1;
    VL p(M), q(M), r(M);
    REP(i, M) {
        cin >> p[i] >> q[i] >> r[i];
        G[p[i]][q[i]] = -r[i];
    }
    REP(k, N) REP(i, N) REP(j, N) { G[i][j] = min(G[i][j], G[i][k] + G[k][j]); }
    ll Mlen = -G[0][N - 1];
    mcf.add_edge(s, 0, LINF, 0);
    mcf.add_edge(N - 1, t, LINF, Mlen);
    REP(i, M) {
        mcf.add_edge(p[i], q[i], LINF, -r[i]);
        mcf.add_edge(p[i], q[i], 1, -r[i] - INF);
    }
    mcf.run(s, t, 100000);
    cout << mcf.min_cost_flow() + M * INF << "\n";
}


Measured memory_bytes: 3420