from collections import deque


n, k = list(map(int, input().split()))
info = [list(map(int, input().split())) for i in range(n - 1)]

tree = [[] for i in range(n)]
for i in range(n - 1):
    a, b = info[i]
    a -= 1
    b -= 1
    tree[a].append(b)
    tree[b].append(a)
    
if n < k:
    print(-1)
    exit()
start = 0
visited = [-1] * n
q = deque([0])
visited[0] = 0
while q:
    pos = q.popleft()
    for next_pos in tree[pos]:
        if visited[next_pos] >= 0:
            continue
        else:
            visited[next_pos] = visited[pos] + 1
            q.append(next_pos)
visited = sorted(visited)
print(sum(visited[0:k]))