import sys
input = sys.stdin.readline

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

E=[tuple(map(int,input().split())) for i in range(N-1)]

EDGE=[[] for i in range(N)]

for a,b,e in E:
    a-=1
    b-=1
    EDGE[a].append((b,e))
    EDGE[b].append((a,e))

QUE=[0] 
Parent=[-1]*(N+1)
Parent[0]=0
TOP_SORT=[]

while QUE:
    x=QUE.pop()
    TOP_SORT.append(x)
    for to,w in EDGE[x]:
        if Parent[to]==-1:
            Parent[to]=x,w
            QUE.append(to)

EW=[0]*N

for n in TOP_SORT[1:][::-1]:
    if EW[n]==0:
        EW[n]=1
    EW[Parent[n][0]]+=EW[n]

XX=[]
for i in range(1,N):
    XX.append((Parent[i][1],EW[i]))

XC=[[] for i in range(101)]

for x,c in XX:
    XC[c].append(x)

ANS=0
cost=0

for i in range(100,-1,-1):
    if sum(XC[i])+cost<=K:
        ANS+=sum(XC[i])*i*2
        cost+=sum(XC[i])
    else:
        rest=K-cost
        DP={0}

        for j in XC[i]:
            NDP=DP.copy()
            for d in DP:
                if d+j<=rest:
                    NDP.add(d+j)
            DP=NDP

        MAX=max(DP)
        SUM=sum(XC[i])
        ANS+=((SUM-MAX)+MAX*2)*i
        cost+=MAX
print(ANS)