from collections import deque

def non_rec_dfs(s):
    stack = []
    stack.append(~s)
    stack.append(s)
    par = [-1] * N
    dist = [0] * N
    inf = 10 ** 18
    pre = [-inf] * (K + 1)
    pre[0] = 0
    leaf = [0] * N
    while stack:
        u = stack.pop()
        if u >= 0:
            stack.append(~u)
            flag = 0
            for v, c in G[u]:
                if v == par[u]:
                    continue
                par[v] = u
                dist[v] = dist[u] + c
                flag = 1
                stack.append(v)
            if not flag:
                leaf[u] = 1
        else:
            u = ~u
            if par[u] == -1:
                continue
            leaf[par[u]] += leaf[u]
            dp = [-inf] * (K + 1)
            cost = D[(par[u], u)]
            for i in range(K + 1):
                dp[i] = pre[i] + cost * leaf[u]
                if i - cost >= 0:
                    dp[i] = max(dp[i], pre[i - cost] + 2 * cost * leaf[u])
            dp, pre = pre, dp
    return max(pre)

N, K = map(int, input().split())
G = [[] for i in range(N)]
D = dict()
for i in range(N - 1):
    a, b, c = map(int, input().split())
    a, b = a - 1, b - 1
    G[a].append((b, c))
    G[b].append((a, c))
    D[(a, b)] = c
    D[(b, a)] = c
    
print(non_rec_dfs(0))