// G++ MACRO.CPP -STD=C++17
#include <bits/stdc++.h>
typedef long long ll;
const int INF = 1e9;
const int MOD = 1e9+7;
const ll LINF = 1e18;
using namespace std;

#define dump(x)  cout << #x << " = " << (x) << endl;
#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define POSSIBLE(n) cout << ((n) ? "POSSIBLE" : "IMPOSSIBLE"  ) << endl
#define Possible(n) cout << ((n) ? "Possible" : "Impossible"  ) << endl
#define possible(n) cout << ((n) ? "possible" : "impossible"  ) << endl

#define SANKOU(n,a,b) cout << ((n) ? (#a) : (#b) ) << endl

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) for(int i=0;i<(n);++i)
#define REPR(i,n) for(int i=n;i>=0;i--)

#define FOREACH(x,a) for(auto& (x) : (a) )

#define WFA(d,v) REP(k,v)REP(i,v)REP(j,v)d[i][j]=min(d[i][j],d[i][k]+d[k][j])

#define SCOUT(x) cout<<(x)<<" "
#define ENDL cout<<endl

#define VECCIN(x) for(auto&youso_: (x) )cin>>youso_
#define VECIN2(x,y) REP(i,x.size())cin>>x[i]>>y[i]
#define VECCOUT(x) if(1){for(auto tt=x.begin();tt!=x.end();tt++){if(tt!=x.begin())cout<<" ";cout<<(*tt);}cout<<endl;}

#define ALL(obj) (obj).begin(),(obj).end()

#define EXIST(n,x) (find(ALL(n),x)!=n.end())
#define UNIQUE(obj) sort(ALL( obj )); obj.erase(unique(ALL(obj)),obj.end())
#define EN(x) if(1){cout<<#x<<endl;return 0;}
#define COUT(x) cout<<(x)<<endl
void CINT(){}
template <class Head,class... Tail>
void CINT(Head&& head,Tail&&... tail){
    cin>>head;
    CINT(move(tail)...);
}
#define CIN(...) int __VA_ARGS__;CINT(__VA_ARGS__)
#define LCIN(...) ll __VA_ARGS__;CINT(__VA_ARGS__)
#define SCIN(...) string __VA_ARGS__;CINT(__VA_ARGS__)

template <class T = ll>
T IN(){T x;cin>>x;return (x);}

template <class Head>
void VT(Head head){}
template <class Head,class Seco,class... Tail>
void VT(Head&& head,Seco&& seco,Tail&&... tail){
    seco.resize(head);
    VT(head,move(tail)...);
}
void VT2(){}
template <class Head,class... Tail>
void VT2(Head&& head,Tail&&... tail){
  VECCIN(head);
  VT2(move(tail)...);
}

template <class Head>
void VT3(Head&& head){}
template <class Head,class Seco,class... Tail>
void VT3(Head&& head,Seco&& seco,Tail&&... tail){
  seco[head]=IN();
  VT3(head,move(tail)...);
}

#define VC1(n,...) V __VA_ARGS__;VT(n,__VA_ARGS__);VT2(__VA_ARGS__); //aaabbbccc
#define VC2(n,...) V __VA_ARGS__;VT(n,__VA_ARGS__);REP(i,n)VT3(i,__VA_ARGS__); //abcabcabc

// #include <boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision; // cpp_int

#define P pair<ll,ll>
#define V vector<ll>
#define M map<ll,ll>
#define S set<ll>

#define pb(a) push_back(a)
#define mp make_pair


int main(){
  CIN(n,k);VC2(n-1,a,b);
  REP(i,n-1){
    a[i]--;
    b[i]--;
  }

  vector<V> edges(n);
  REP(i,n-1){
    edges[a[i]].pb(b[i]);
    edges[b[i]].pb(a[i]);
  }
  auto choku = [&](int nn){
    V dif(n,-1);

    std::function<void(int,int)> d = [&](int pos,int num){
      dif[pos]=num;
      FOREACH(xx,edges[pos]){
        if(dif[xx]!=-1)continue;
        d(xx,num+1);
      }
    };
    d(nn,0);
    M mm;REP(i,n)mm[dif[i]]=i;
    return (*prev(mm.end()));
  };
  P p1 = choku(0);
  P p2 = choku(p1.second);
  if(k>=p2.first)EN(0);

  if(k%2==0){

    auto pd = [&](int nn){

      V dif(n,-1);

      function<void(int,int)> d = [&](int pos,int num){
        dif[pos]=num;
        FOREACH(xx,edges[pos]){
          if(dif[xx]!=-1)continue;
          d(xx,num+1);
        }
      };
      d(nn,0);
      ll ret = 0;
      REP(i,n)
        ret+=(dif[i]>k/2);
      return ret;
    };

    ll ans = LINF;
    REP(i,n)
      ans = min(ans,pd(i));
    COUT(ans);
    return 0;
  }
  auto ed = [&](int nn){
    vector<V> dif(2,V(n,-1));
      function<void(int,int,int)> d = [&](int side,int pos,int num){
        dif[side][pos]=num;
        FOREACH(xx,edges[pos]){
          if(dif[side][xx]!=-1)continue;
          d(side,xx,num+1);
        }
      };
    
    d(0,a[nn],1);
    d(1,b[nn],1);
    ll ret=0;
    REP(i,n)
      ret += (min(dif[0][i],dif[1][i]) > (k+1)/2);



    return ret;
  };

  ll ans = LINF;
  REP(i,n-1)
    ans = min(ans,ed(i));
  COUT(ans);
  return 0;
}


Measured memory_bytes: 640