import sys
input = sys.stdin.readline

from collections import deque
def bfs(G, s):
    Q = deque([s])
    N = len(G)
    dist = [-1] * N
    par = [-1] * N
    dist[s] = 0
    while Q:
        u = Q.popleft()
        for v in G[u]:
            if dist[v] != -1:
                continue
            dist[v] = dist[u] + 1
            par[v] = u
            Q.append(v)

    return dist


N, K = map(int, input().split())
G = [[] for i in range(N)]
for i in range(N - 1):
    a, b = map(int, input().split())
    a, b = a - 1, b - 1
    G[a].append(b)
    G[b].append(a)
    
if K >= N + 1:
    print(-1)
    exit()
    
print(sum(sorted(bfs(G, 0))[:K]))