#include<bits/stdc++.h>
using namespace std;
#define ALL(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define INF 1000000000
#define mod 1000000007
using ll=long long;
const ll LINF=1001002003004005006ll;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return true;}return false;}

int n,k;
vector<int> dep;
vector<vector<int>> g;

void dfs(int pre,int now){
    for(auto to:g[now])if(to!=pre){
        dep[to]=dep[now]+1;
        dfs(now,to);
    }
}

signed main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    cin>>n>>k;
    dep.resize(n,0);g.resize(n);
    rep(i,n-1){
        int a,b;cin>>a>>b;a--,b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    if(k>n){
        cout<<-1<<endl;
        return 0;
    }
    dfs(-1,0);
    sort(ALL(dep));
    // debug(dep);
    int ans=0;
    for(int i=1;i<k;i++){
        ans+=dep[i];
    }
    cout<<ans<<endl;
    return 0;
}