// #pragma GCC optimize(3,"Ofast","inline")
// #pragma GCC optimize(2)
#include <bits/stdc++.h>
using namespace std;
#define all(v) v.begin(), v.end()
#define point(n) fixed << setprecision(n)
#define IOS                      \
    ios::sync_with_stdio(false); \
    cin.tie(0), cout.tie(0);
#define endl '\n'
#define inf 0x3f3f3f3f
typedef long long ll;
typedef pair<ll, ll> PII;
typedef pair<ll, array<ll, 2>> PIA;
const int N = 1e6 + 10,mod=998244353;
const ll INF = 0x3f3f3f3f3f3f3f3f;
int  n, m, k;
int  f[N];
vector<int >h[N];
void solve()
{
    cin >> n >> m;
    int cnt=n+2*m;
    for(int i=1;i<n;i++){
        int a,b;
        cin >> a >> b;
        h[a].push_back(b);
        h[b].push_back(a);
    }
    if(n&1){
        cout<<(n+m)/2<<'\n';
    }else {
         cout<<m<<'\n';
    }
    
}
int main()
{
    IOS;
    int _ = 1;
    //cin >> _;
    while (_--)
    {
        solve();
    }
    return 0;
}