n, m = map(int, input().split()) ans = [[0 if i == j else float("inf") for i in range(n)] for j in range(n)] for i in range(m): a, b, c = map(int, input().split()) ans[a-1][b-1] = c for k in range(n): for i in range(n): for j in range(n): if ans[i][k] != float("inf") and ans[k][j] != float("inf"): ans[i][j] = min(ans[i][j], ans[i][k]+ans[k][j]) for i in range(n): cnt = 0 for j in range(n): if ans[i][j] != float("inf"): cnt += ans[i][j] print(cnt)