N, K = map(int, input().split())
adj = [[] for i in range(N)]
E = []
for i in range(N - 1):
    a, b, c = map(int, input().split())
    a -= 1
    b -= 1
    adj[a].append((b, c))
    adj[b].append((a, c))
    E.append((a, b, c))
depth = [-1] * N
depth[0] = 0
from collections import deque
qu = deque([0])
while len(qu):
    v = qu.popleft()
    for nv, c in adj[v]:
        if depth[nv] == -1:
            depth[nv] = depth[v] + c
            qu.append(nv)
dp = [1] * N
for v in range(N):
    for nv, c in adj[v]:
        if depth[nv] > depth[v]:
            dp[v] = 0
            break
ans = sum([dp[i] * depth[i] for i in range(N)])
node = [i for i in range(N)]
node.sort(key = lambda x: depth[x], reverse = True)

for v in node:
    for nv, c in adj[v]:
        if depth[nv] < depth[v]:
            continue
        dp[v] += dp[nv]
V = []
for i in range(N - 1):
    a, b, c = E[i]
    if depth[a] > depth[b]:
        a, b = b, a
    #aが浅い
    V.append(c * dp[b])

dp = [[0] * (K + 1) for i in range(N)]
for i in range(N - 1):
    for j in range(K + 1):
        dp[i + 1][j] = dp[i][j]
        if j + E[i][2] <= K:
            dp[i + 1][j] = max(dp[i + 1][j], dp[i][j + E[i][2]] + V[i])
print(max(dp[-1]) + ans)