#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
using namespace std;
vector <pair<int,int>> G[100005];
int n,k;
#define MAXN 100005
typedef int var;
int grade[100005],tati[100005];
vector <int> costs;
void read()
{
    cin>>n>>k;
    for(int i=0; i<n-1; i++)
    {
        int a,b,c;
        cin>>a>>b>>c;
        G[a].push_back({b,c});
        G[b].push_back({a,c});
        grade[a]++;
        grade[b]++;
        if(a>b)
            swap(a,b);
        tati[b]=a;
    }
    tati[1]=0;
}
const int64_t INF = 1e9;
void dijkstra(int start)
{
    vector <int> dist(n+1,INF);
    dist[start]=0;
    int u;
    set<pair<int,int> > s;
    s.insert({dist[start], start});
    while(!s.empty())
    {
        u = s.begin() -> second;
        s.erase(s.begin());
        for(auto p : G[u])
            if(dist[p.first]>dist[u]+p.second)
            {
                s.erase({dist[p.first],p.first});
                dist[p.first]=dist[u]+p.second;
                s.insert({dist[p.first],p.first});
            }
    }
    for(int y=start+1; y<=n; y++)
        if(y!=start && dist[y]!=INF)
            costs.push_back(dist[y]);

   /* for(auto x:G[start])
    {
        int i=x.first;
        for(int j=0;j<G[i].size();j++)
        {
            auto y = G[i][j];
            if(y.first==start)
            {
        G[i].erase(begin(G[i])+j);
            break;
            }
        }
    }*/
    G[start].clear();
}
int main()
{
    read();

    for(int i=1; i<=n; i++)
        if(grade[i]>1)
            dijkstra(i);
    sort(begin(costs),end(costs));
    if(k>costs.size())
        cout<<"-1";
    else
        cout<<costs[k-1]<<"\n";

}