#994
from collections import deque

N,K = map(int,input().split())
edge = [[] for _ in range(N)]
for _ in range(N-1):
    a,b = map(int,input().split())
    edge[a-1].append(b-1)
    edge[b-1].append(a-1)
if N < K:
    print(-1)
else:
    distance = [-1]*N
    distance[0] = 0
    q = deque([0])
    while q:
        now = q.popleft()
        for v in edge[now]:
            if distance[v] != -1:
                continue
            else:
                distance[v] = distance[now]+1
                q.append(v)
    distance.sort()
    dist = distance[1:]
    ans = 0
    for i in range(K-1):
        ans += dist[i]
    print(ans)