#include <bits/stdc++.h>
#define inf 1000000007
#define mod 1000000007
// #define int long long
// #pragma GCC optimize("Ofast","inline","-ffast-math")
// #pragma GCC target("avx,sse2,sse3,sse4,mmx")
using namespace std;
template <typename T> void read(T &x){
	x=0;char ch=getchar();int fh=1;
	while (ch<'0'||ch>'9'){if (ch=='-')fh=-1;ch=getchar();}
	while (ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
	x*=fh;
}
template <typename T> void write(T x) {
	if (x<0) x=-x,putchar('-');
	if (x>9) write(x/10);
	putchar(x%10+'0');
}
template <typename T> void writeln(T x) {
	write(x);
	puts("");
}
int n,m;
vector<pair<int,int>> g[100005];
namespace bp1
{
	int dp[5005][5005],tmp[5005],siz[5005];
	void dfs(int x,int fa)
	{
		dp[x][0]=dp[x][1]=0;siz[x]=1;
		for(auto i:g[x])
		{
			if(i.first==fa) continue;
			dfs(i.first,x);
			for(int j=0;j<=min(siz[x]+siz[i.first],m);++j)
				tmp[j]=-inf;
			for(int j=0;j<=min(siz[x],m);++j)
				for(int k=0;k<=min(siz[i.first],m-j);++k)
					tmp[j+k]=max(tmp[j+k],dp[x][j]+dp[i.first][k]+i.second*k*(m-k));
			siz[x]+=siz[i.first];
			for(int j=0;j<=min(siz[x],m);++j)
				dp[x][j]=tmp[j];
		}
	}
	void solve()
	{
		memset(dp,-0x3f,sizeof(dp));
		dfs(1,0);
		writeln(dp[1][m]);
	}
}
namespace bp2
{
	int dp[100005][3],tmp[3],siz[100005];
	void dfs(int x,int fa)
	{
		dp[x][0]=dp[x][1]=0;siz[x]=1;
		for(auto i:g[x])
		{
			if(i.first==fa) continue;
			dfs(i.first,x);
			for(int j=0;j<=min(siz[x]+siz[i.first],m);++j)
				tmp[j]=-inf;
			for(int j=0;j<=min(siz[x],m);++j)
				for(int k=0;k<=min(siz[i.first],m-j);++k)
					tmp[j+k]=max(tmp[j+k],dp[x][j]+dp[i.first][k]+i.second*k*(m-k));
			siz[x]+=siz[i.first];
			for(int j=0;j<=min(siz[x],m);++j)
				dp[x][j]=tmp[j];
		}
	}
	void solve()
	{
		memset(dp,-0x3f,sizeof(dp));
		dfs(1,0);
		writeln(dp[1][m]);
	}
}
signed main()
{
	// freopen("bigdata.in","r",stdin);
	// freopen("bigdata.out","w",stdout);
	read(n);read(m);
	for(int i=1;i<n;++i)
	{
		int a,b,c;
		read(a);read(b);read(c);
		g[a].push_back({b,c});
		g[b].push_back({a,c});
	}
	if(n<=5000) bp1::solve();
	else if(m==2) bp2::solve();
	return 0;
}