n, k = map(int, input().split())
if n < k:
    print(-1)
    exit(0)
g = [[] for _ in range(n)]
for _ in range(n - 1):
    a, b = map(int, input().split())
    g[a - 1].append(b - 1)
    g[b - 1].append(a - 1)
s = [0]
d = [-1] * n
d[0] = 0
while s:
    p = s.pop()
    for node in g[p]:
        if d[node] == -1:
            d[node] = d[p] + 1
            s.append(node)
d.sort()
print(sum(d[:k]))