N, K = map(int, input().split())

v = [[[], []] for _ in range(N)]
weight = []
for i in range(N-1):
    a, b, c = map(int, input().split())
    v[a-1][1].append((b-1, i))
    v[b-1][1].append((a-1, i))
    weight.append(c)
    
q = [(0, [])]
e = [0] * (N-1)
while len(q) > 0:
    i, c = q.pop(0)
    v[i][0] = c
    cnt = True
    for j, k in v[i][1]:
        if j == 0 or len(v[j][0]) > 0:
            continue
        cnt = False
        q.append((j, c+[k]))
    if cnt:
        for j in c:
            e[j] += 1

d = dict()

def dfs(i, val, k):
    if (i, val, k) in d:
        return d[(i, val, k)]
    if i == N-1:
        return val
    if weight[i] > k:
        ret = dfs(i+1, val+weight[i]*e[i], k)
    else:
        ret = max(dfs(i+1, val+weight[i]*e[i], k), dfs(i+1,  val+weight[i]*e[i]*2, k-weight[i]))
    d[(i, val, k)] = ret
    return ret

print(dfs(0, 0, K))