import queue
from collections import namedtuple
from sys import maxsize as inf
P = namedtuple("P", "i c")

n, k = map(int, input().split())
path = []
cst = []

for i in range(n):
    path.append(set())
    cst.append(inf)

for _ in range(n - 1):
    a, b = [int(x) - 1 for x in input().split()]
    path[a] |= {b}
    path[b] |= {a}

q = queue.Queue()
q.put(P(1, 0))
while q.qsize() != 0:
    p = q.get()
    if cst[p.i] <= p.c: continue
    cst[p.i] = p.c
    for j in path[p.i]:
        q.put(P(j, p.c + 1))

cst.sort()
if n < k: print(-1)
else: print(sum(cst[:k]))