V - I.O.U. 2

#include <bits/stdc++.h>

using namespace std;

#define fixed(n) fixed << setprecision(n)
#define ceil(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define add_mod(a, b, m) (((a % m) + (b % m)) % m)
#define sub_mod(a, b, m) (((a % m) - (b % m) + m) % m)
#define mul_mod(a, b, m) (((a % m) * (b % m)) % m)
#define all(vec) vec.begin(), vec.end()
#define rall(vec) vec.rbegin(), vec.rend()
#define sz(x) int(x.size())
#define debug(x) cout << #x << ": " << (x) << "\n";
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define Mod  1'000'000'007
#define EPS 1e-9
constexpr int INF = 1 << 30;
constexpr ll LINF = 1LL << 62;
#define PI acos(-1)
template < typename T = int > using Pair = pair < T, T >;
vector < string > RET = {"NO", "YES"};

template < typename T = int > istream& operator >> (istream &in, vector < T > &v) {
    for (auto &x : v) in >> x;
    return in;
}

template < typename T = int > ostream& operator << (ostream &out, const vector < T > &v) {
    for (const T &x : v) out << x << ' ';
    return out;
}

// a -> b = 10
// b -> c = 10

// c = 10
// a = 0
// b = 0

void Solve(){
    int n, m;
    cin >> n >> m;
    vector < int > debt(n + 5);
    for(int i = 0, a, b, c; i < m; i++){
        cin >> a >> b >> c;
        debt[a] += c;
        debt[b] -= c;
    }
    int min_sum = 0;
    for(int i = 1; i <= n; i++)
        if(debt[i] < 0)
            min_sum -= debt[i];
    cout << min_sum << '\n';
}

int main(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    int test_cases = 1;
    // cin >> test_cases;
    for(int tc = 1; tc <= test_cases; tc++){
        // cout << "Case #" << tc << ": ";
        Solve();
    }
    return 0;
}