import sys
input = sys.stdin.readline

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

if K>N:
    print(-1)
    sys.exit()

E=[[] for i in range(N+1)]
ANS=[-1]*(N+1)

for i in range(N-1):
    x,y=map(int,input().split())
    E[x].append(y)
    E[y].append(x)

from collections import deque

Q=deque()
Q.append(1)
ANS[1]=0
while Q:
    x=Q.popleft()
    for to in E[x]:
        if ANS[to]==-1:
            ANS[to]=ANS[x]+1
            Q.append(to)

ANS.sort()
print(sum(ANS[1:1+K]))