#include <bits/stdc++.h>

using namespace std;

const int N = 321123;

int n, k, ans, black[N], white[N];
vector<int> g[N];

void dfs(int v, int p, int x) {
	black[v] = N;
	white[v] = 0;
	for (auto u : g[v]) {
		if (u == p) continue;
		dfs(u, v, x);
		if (black[v] + 1 + white[u] <= x) 
			white[u] = -1;
		if (black[u] + 1 + white[v] <= x)
			white[v] = -1;
		if (white[u] != -1)
			white[v] = max(white[v], white[u] + 1);
		black[v] = min(black[v], black[u] + 1);
	}
	if (white[v] == x || (white[v] != -1 && v == 1)) {
		ans++;
		white[v] = -1;
		black[v] = 0;
	}
}

int main() {
	cin >> n >> k;
	for (int i = 0; i < n - 1; i++) {
		int a, b; cin >> a >> b;
		g[a].push_back(b);
		g[b].push_back(a);
	}
	int l = 1, r = n - 1;
	while (l < r) {
		int m = (l + r) / 2;
		ans = 0;
		dfs(1, 0, m);
		if (ans <= k)
			r = m;
		else
			l = m + 1;
	}
	cout << l << "\n"; 
	return 0;
}

#pragma GCC optimize ("O2")
#pragma GCC target ("avx2")
//#include<bits/stdc++.h>
//#include<atcoder/all>
//using namespace atcoder;
#include<cstdio>
#include<cstring>

using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

int to[400001], ne[400001], he[200001];
int Q[200001], pl[200001], dl[200001];

const int CM = 1 << 17, CL = 12;
char cn[CM + CL], * ci = cn + CM + CL, * owa = cn + CM, ct;
const ll ma0 = 1157442765409226768;
const ll ma1 = 1085102592571150095;
const ll ma2 = 71777214294589695;
const ll ma3 = 281470681808895;
const ll ma4 = 4294967295;
inline int getint() {
	if (ci - owa > 0) {
		memcpy(cn, owa, CL);
		ci -= CM;
		fread(cn + CL, 1, CM, stdin);
	}
	ll tmp = *(ll*)ci;
	int dig = 68 - __builtin_ctzll((tmp & ma0) ^ ma0);
	tmp = tmp << dig & ma1;
	tmp = tmp * 10 + (tmp >> 8) & ma2;
	tmp = tmp * 100 + (tmp >> 16) & ma3;
	tmp = tmp * 10000 + (tmp >> 32) & ma4;
	ci += 72 - dig >> 3;
	return tmp;
}

int main() {
	//cin.tie(0);
	//ios::sync_with_stdio(false);


	int N = getint(), K = getint();
	int k = 1;
	rep(i, N - 1) {
		int u = getint(), v = getint();
		to[k] = v;
		ne[k] = he[u];
		he[u] = k++;
		to[k] = u;
		ne[k] = he[v];
		he[v] = k++;
	}

	int q = 0, p = 0;
	Q[q++] = 1;
	while (p < N) {
		int u = Q[p++];
		int tmp = 0;
		int ind = he[u];
		he[u] = 0;
		while (ind) {
			int v = to[ind];
			tmp = ne[ind];
			if (he[v] > 0) {
				Q[q++] = v;
				ne[ind] = he[u];
				he[u] = -ind;
			}
			ind = tmp;
		}
	}

	int are = 1000000, pd0 = are;
	int L = 0, R = (N + K - 1) / K;
	while (L + 1 < R) {
		int wj = (L + R) / 2;

		int num = 0;

		for (int i = N - 1; i >= 0; i--) {
			int po = pd0 - 1;
			int dd = pd0;
			int u = Q[i];
			for (int ind = -he[u]; ind; ind = -ne[ind]) {
				int v = to[ind];
				if (po < pl[v]) po = pl[v];
				if (dd < dl[v]) dd = dl[v];
			}
			if (po >= dd) dd = 0;
			if (dd >= pd0 + wj) {
				num++;
				po = pd0 + wj;
				dd = 0;
			}
			pl[u] = po - 1;
			dl[u] = dd + 1;
			if (num > K) break;
		}

		int are = num + (dl[1] > pd0);
		if (are > K) L = wj;
		else R = wj;

		pd0 += are;
	}

	printf("%d", R);

	Would you please return 0;
}