#include<bits/stdc++.h>
using namespace std;

const int nmax=5e3+42,kmax=5e2+42;

int n,k;

int bits(int w)
{
    int ret=0;

    while(w)
    {
        ret=ret+w%2;
        w=w/2;
    }

    return ret;
}

vector< pair<int,int> > adj[nmax];

int help[nmax][kmax];

int SZ[nmax];

vector<int> rec(int node,int parent)
{
    vector<int> outp={0};

    for(auto w:adj[node])
        if(w.first!=parent)
        {
            vector<int> cur=rec(w.first,node);

            vector<int> help(outp.size()+cur.size()-1,n);


            //cout<<"w= "<<w.first<<" -> ";for(auto w:cur)cout<<w<<" ";cout<<endl;

            if(w.second==0)
            {
                for(int i=0;i<outp.size();i++)
                    for(int j=0;j+1<cur.size();j++)
                    {
                        help[i+j]=min(help[i+j],outp[i]+cur[j]);

                        //flip w
                        help[i+SZ[w.first]-j]=min(help[i+SZ[w.first]-j],outp[i]+cur[j]+1);
                    }
            }
            else
            {
                for(int i=0;i<outp.size();i++)
                    for(int j=0;j+1<cur.size();j++)
                    {
                        //cout<<i<<" "<<j<<endl;

                        help[i+SZ[w.first]-j]=min(help[i+SZ[w.first]-j],outp[i]+cur[j]);

                        //cout<<"upd "<<i+SZ[w.first]-j<<" "<<outp[i]+cur[j]<<endl;

                        //flip w
                        help[i+j]=min(help[i+j],outp[i]+cur[j]+1);

                        //cout<<"upd "<<i+j<<" "<<outp[i]+cur[j]+1<<endl;
                    }
            }

                outp=help;
                continue;
        }

    outp.push_back(outp.back()+1);

    //cout<<"node= "<<node<<" -> ";for(auto w:outp)cout<<w<<" ";cout<<endl;

    return outp;
}

void dfs(int node,int parent)
{
    SZ[node]=1;

    for(auto w:adj[node])
        if(w.first!=parent)
        {
            dfs(w.first,node);
            SZ[node]=SZ[node]+SZ[w.first];
        }
}

int solve()
{
    scanf("%i%i",&n,&k);

    for(int i=1;i<n;i++)
    {
        int u,v,w;
        scanf("%i%i%i",&u,&v,&w);

        w=bits(w)%2;

        adj[u].push_back({v,w});
        adj[v].push_back({u,w});

        //cout<<u<<" "<<v<<" -> "<<w<<endl;
    }

    dfs(1,1);

    vector<int> outp=rec(1,1);

    int mini=n*n;

    for(int i=0;i<n;i++)
    {
        if(outp[i]<=k)
        {
            mini=min(mini,i*(n-i));
        }
    }

    return mini;
}

int main()
{
    freopen("xorfun.in","r",stdin);
    freopen("xorfun.out","w",stdout);

    int t;
    t=1;

    while(t)
    {
        t--;
        printf("%i\n",solve());
    }

    return 0;
}