#include <bits/stdc++.h>
#define Nmax 1002
using namespace std;

ifstream fin("salvare.in");
ofstream fout("salvare.out");

int N, K, nr;
int dp[Nmax];
vector<int> G[Nmax];

void DFS(int node, int father, int val, int dist) {
    int len = dist; bool leaf = 1;
    for (auto it: G[node])
        if (it != father) leaf = 0;
    if (dist == val && !leaf) len = 0, ++nr;

    for (auto it: G[node])
        if (it != father) DFS(it, node, val, len + 1);
}
bool check(int val) {
    for (int i = 1; i <= N; ++i) {
        nr = 1;
        DFS(i, 0, val, 0);
        if (nr <= K) return 1;
    }
      return 0;
}
int main()
{
    fin >> N >> K;
    for (int i = 1; i < N; ++i) {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

    int le = 1, ri = N, ans = N;
    while (le <= ri) {
        int mid = (le + ri) / 2;
        if (check(mid)) ans = mid, ri = mid - 1;
        else le = mid + 1;
    }
    fout << ans << '\n';

    return 0;
}