public static void main(String[] args) {
 Scanner in = new Scanner(System.in);
 int n = in.nextInt();
 int m = in.nextInt();
 long[] output = new long[n];
 IntStream.range(0,m).forEach(i -> { int a = in.nextInt()-1;
                                    int b = in.nextInt();
                                    int k = in.nextInt();
                                    output[a] += k;
                                    if(b < n) output[b] -= k; });
 AtomicLong sum = new AtomicLong(0);
 System.out.print(LongStream.of(output).map(sum::addAndGet)
                                       .max().getAsLong());
 in.close();
}