Problem 3

// author : compounding
#include <bits/stdc++.h>
using namespace std;

const int MAXN = 200005;
int start[MAXN], end[MAXN], subtree_size[MAXN], diff[MAXN], timer = 0;
vector<int> adj[MAXN];

void dfs(int node, int parent) {
    start[node] = timer++;
    subtree_size[node] = 1;
    for (int neighbor : adj[node]) {
        if (neighbor != parent) {
            dfs(neighbor, node);
            subtree_size[node] += subtree_size[neighbor];
        }
    }
    end[node] = timer;
}

int main() {
    int N, K;
    cin >> N >> K;

    for (int i = 1; i < N; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    dfs(1, -1);

    for (int i = 1; i <= N; i++) {
        if (subtree_size[i] <= K) {
            diff[start[i]]++;
            if (end[i] < N) diff[end[i]]--;
        }
    }

    int result = 0;
    for (int i = 1; i < N; i++) {
        diff[i] += diff[i - 1];
        if (diff[i] > 0) result++;
    }

    cout << result << endl;

    return 0;
}