#include<iostream>

#include<cstdio>

#include<cstring>

using namespace std;

const int maxn=2009;

typedef long long Lint;

int n,m;

int cntedge=0;

int head[maxn]={0};

int to[maxn<<1],nex[maxn<<1],dist[maxn<<1];

void Addedge(int x,int y,int z){

	nex[++cntedge]=head[x];

	to[cntedge]=y;

	dist[cntedge]=z;

	head[x]=cntedge;

}

Lint f[maxn][maxn];

Lint g[maxn];

int siz[maxn];

void Dp(int x,int fa){

	for(int i=head[x];i;i=nex[i]){

		int v=to[i];

		if(to[i]==fa)continue;

		Dp(v,x);

		memset(g,0,sizeof(g));

		for(int j=0;j<=siz[x];++j){

			for(int k=0;k<=siz[v];++k){

				Lint tm=max(f[v][k],k?f[v][k-1]:0)+f[x][j]+1LL*k*(m-k)*dist[i]+1LL*(siz[v]-k)*(n-m-siz[v]+k)*dist[i];

				g[j+k]=max(g[j+k],tm);

			}

		}

		siz[x]+=siz[v];

		for(int j=0;j<=siz[x];++j)f[x][j]=g[j];

	}

	++siz[x];

}

int main(){

	scanf("%d%d",&n,&m);

	for(int i=1;i<=n-1;++i){

		int x,y,z;

		scanf("%d%d%d",&x,&y,&z);

		Addedge(x,y,z);

		Addedge(y,x,z);

	}

	Dp(1,0);

	cout<<max(f[1][m],f[1][m-1]);

	cout<<endl;

	return 0;

}