N, M = map(int, input().split())
item1 = [0] * M
item2 = [0] * M
score = [0] * M
sei_score = 0
gyaku_score = 0
for i in range(M):
    item1[i], item2[i], score[i] = map(int, input().split())
    if item1[i] < item2[i]:
        sei_score += score[i]
    if item1[i] > item2[i]:
        gyaku_score += score[i]

if sei_score > gyaku_score:
    print(sei_score)
else:
    print(gyaku_score)