# coding: utf-8
# Your code here!
def dfs(num,count):
    visited[num]=count
    for item in way[num]:
        if visited[item] == -1:
            dfs(item,count+1)
    return 

N,K=map(int,input().split())

way=[[] for i in range(N)]
visited=[-1]*N

for _ in range(N-1):
    a,b=map(int,input().split())
    way[a-1].append(b-1)
    way[b-1].append(a-1)

dfs(0,0)

visited.sort()
if len(visited)<K:
    print(-1)
else:
    print(sum(visited[:K]))