n, k = map(int, input().split())
G = [[] for _ in range(n)]
for _ in range(n-1):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    G[a].append(b)
    G[b].append(a)

if k > n:
    print(-1)
    exit()

d = [-1] * n
d[0] = 0
que = [0]
while que:
    s = que.pop()
    for t in G[s]:
        if d[t] == -1:
            d[t] = d[s] + 1
            que.append(t)

d.sort()
print(sum(d[:k]))