#include <bits/stdc++.h>
#define ull unsigned long long
#define ll long long
using namespace std;
const int N=2005;
int n,m,k,s,t,size[N];
ll f[N][N],g[N];
vector<pair<int,ll>> e[N];
void dfs(int u,int fa){
	f[u][0]=f[u][1]=0;
	size[u]=1;
	for (auto &o:e[u]){
		int v=o.first;
		if (v==fa) continue;
		dfs(v,u);
		for (int i=size[u];i>=0;--i)
			for (int j=size[v];j>=0;--j)//因为j会取到0，所以j也需要倒序枚举 
				f[u][i+j]=max(f[u][i+j],f[u][i]+f[v][j]+o.second*(j*(m-j)+(size[v]-j)*(n-m-size[v]+j)));
		size[u]+=size[v];
	}
}
int main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0); 
    cin>>n>>m;
    for (int i=1;i<n;++i){
		cin>>s>>t>>k;
		e[s].push_back({t,k});
		e[t].push_back({s,k});	
	}
	dfs(1,0);
	cout<<f[1][m];
}