#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define xprintf(fmt,...) fprintf(stderr,fmt,__VA_ARGS__)
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(auto cnt=0ll;cnt<(l);++cnt)
#define iterate(cnt,b,e) for(auto cnt=(b);cnt!=(e);++cnt)
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
template<typename T1, typename T2> ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }
template<typename iterator> inline size_t argmin(iterator begin, iterator end) { return distance(begin, min_element(begin, end)); }
template<typename iterator> inline size_t argmax(iterator begin, iterator end) { return distance(begin, max_element(begin, end)); }
template<typename T> T& maxset(T& to, const T& val) { return to = max(to, val); }
template<typename T> T& minset(T& to, const T& val) { return to = min(to, val); }

mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
    return uniform_int_distribution<ll>(l, h)(randdev);
}

#ifdef __MAI
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
#ifdef __VSCC
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T> void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        inline MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiblechar(cc); cc = getchar_unlocked());
            for (; isvisiblechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
            return *this;
        }
        template<typename IT> void in(IT begin, IT end) {
            for (auto it = begin; it != end; ++it) *this >> *it;
        }
    };
}
MaiScanner scanner;


class Graph {
public:
    size_t n;
    vector<vector<int>> vertex_to;

    Graph(size_t n) :n(n), vertex_to(n) {}

    void connect(int from, int to) {
        vertex_to[from].emplace_back(to);
        vertex_to[to].emplace_back(from);
    }
    void resize(size_t _n) {
        n = _n;
        vertex_to.resize(_n);
    }
};



ll m, n, kei;

ll center;
Graph graph(1);
vector<pair<int, int>> edges;


int main() {

    scanner >> n >> kei;

    m = n - 1;
    graph.resize(n);

    repeat(i, m) {
        int a, b;
        scanner >> a >> b;
        --a; --b;
        graph.connect(a, b);
        edges.emplace_back(a, b);
    }


    ll len;
    {
        ll far = 0;
        {
            ll dist = 0;
            function<void(int, int, int)> dfs1 = [&](int idx, int from, int d) {
                if (dist < d) {
                    dist = d;
                    far = idx;
                }
                for (int to : graph.vertex_to[idx]) {
                    if (to == from) continue;
                    dfs1(to, idx, d + 1);
                }
            };
            dfs1(0, -1, 0);
        }

        ll far2 = 0;
        {
            ll dist = 0;
            function<void(int, int, int)> dfs2 = [&](int idx, int from, int d) {
                if (dist < d) {
                    dist = d;
                    far2 = idx;
                }
                for (int to : graph.vertex_to[idx]) {
                    if (to == from) continue;
                    dfs2(to, idx, d + 1);
                }
            };
            dfs2(far, -1, 0);
            len = dist;
        }
    }

    if (len <= kei) {
        cout << 0 << endl;
        return 0;
    }

    if (kei % 2 == 0) {
        function<int(int, int, int)> dfs3 = [&](int idx, int from, int d) {
            int cnt = 0;
            for (int to : graph.vertex_to[idx]) {
                if (to == from) continue;
                cnt += dfs3(to, idx, d + 1);
            }
            return cnt + (kei / 2 < d);
        };

        int best = n;
        repeat(i, n) {
            minset(best, dfs3(i, -1, 0));
        }
        cout << best << endl;
    }
    else {
        function<int(int, int, int)> dfs4 = [&](int idx, int from, int d) {
            int cnt = 0;
            for (int to : graph.vertex_to[idx]) {
                if (to == from) continue;
                cnt += dfs4(to, idx, d + 1);
            }
            return cnt + (kei / 2 < d);
        };

        int best = n;
        for (auto edge : edges) {
            int u = edge.first;
            int v = edge.second;
            minset(best, dfs4(u, v, 0) + dfs4(v, u, 0));
        }
        cout << best << endl;
    }



    return 0;
}

Measured memory_bytes: 512