#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


# %%
N, K = map(int, readline().split())
m = map(int, read().split())
AB = tuple(zip(m, m))

# %%
graph = [[] for _ in range(N + 1)]
for a, b in AB:
    graph[a].append(b)
    graph[b].append(a)

# %%
dist = [0] * (N + 1)
parent = [0] * (N + 1)
stack = [1]
while stack:
    v = stack.pop()
    for w in graph[v]:
        if w == parent[v]:
            continue
        parent[w] = v
        stack.append(w)
        dist[w] = dist[v] + 1

# %%
dist = sorted(dist[1:])

# %%
if K > N:
    answer = -1
else:
    answer = sum(dist[:K])
print(answer)