#include constexpr long long MAX = 1000000000000; constexpr long long INF = 99000000000001; int main() { int N, M; std::cin >> N >> M; assert(2 <= N && N <= 100); assert(1 <= M && M <= 9900); std::vector> edges(M); for (auto &[a, b, c]: edges) { std::cin >> a >> b >> c; assert(1 <= a && a <= N); assert(1 <= b && b <= N); assert(a != b); assert(-MAX <= c && c <= MAX); a -= 1; b -= 1; } for (int src = 0; src < N; ++src) { std::vector dist(N, INF); dist[src] = 0; for (int step = 0; step < 2 * N; ++step) { assert(step != N); bool change = false; for (const auto [a, b, c]: edges) { if (dist[a] != INF && dist[b] > dist[a] + c) { dist[b] = dist[a] + c; change = true; } } if (!change) { break; } } long long ans = 0; for (int i = 0; i < N; ++i) { if (dist[i] < INF) { ans += dist[i]; } } std::cout << ans << '\n'; } return 0; }