#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
    int n, k;
    cin>>n>>k;
    if(k>n){
        cout<<-1<<endl;
        return 0;
    }else{
        cout<<k-1<<endl;
        return 0;
    }
    vector<int> g[100010];
    for(int i=0; i<n-1; i++){
        int a, b;
        cin>>a>>b;
        a--; b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    ll d[100010];
    d[0]=0;
    auto dfs=[&](auto dfs, int x, int p)->void{
        for(auto y:g[x]){
            if(y==p) continue;
            d[y]=d[x]+1;
            dfs(dfs, y, x);
        }
    };
    dfs(dfs, 0, -1);
    sort(d, d+n);
    ll ans=0;
    for(int i=0; i<k; i++) ans+=d[i];
    cout<<ans<<endl;
    return 0;
}