#include <bits/stdc++.h>
using namespace std;
const long long MAX = 1e6 + 1;
void solve() {
  long long n, m;
  cin >> n >> m;
  if (m == 0) {
    cout << 0;
    return;
  }
  long long total[n + 1];
  memset(total, 0, sizeof(total));
  long long ai, bi, ci;
  for (long long i = 0; i < m; i++) {
    cin >> ai >> bi >> ci;
    total[ai] -= ci;
    total[bi] += ci;
  }
  long long ans = 0;
  for (long long i = 0; i < n + 1; i++) {
    if (total[i] > 0) {
      ans += total[i];
    }
  }
  cout << ans;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long t;
  t = 1;
  while (t--) {
    solve();
  }
}
