/**************************************************************

     Problem: 4033

     User: idy002

     Language: C++

     Result: Accepted

     Time:6568 ms

     Memory:32492 kb

 ****************************************************************/

 #include <cstdio>

 #define min(a,b) ((a)<(b)?(a):(b))

 #define max(a,b) ((a)>(b)?(a):(b))

 #define oo 0x3f3f3f3f3f3f3f3fLL

 #define N 2010 

 typedef long long dnt; 

 int n, m;

 int head[N], next[N+N], dest[N+N], wght[N+N], etot;

 dnt siz[N];

 dnt dp[N][N], pp[N]; 

 void adde( int u, int v, int w ) {

     etot++;

     wght[etot] = w;

     dest[etot] = v;

     next[etot] = head[u];

     head[u] = etot;

 }

 void dfs( int u, int fa ) {

     siz[u] = ;

     for( int t=head[u]; t; t=next[t] ) {

         int v=dest[t];

         if( v==fa ) continue;

         dfs( v, u );

         siz[u] += siz[v];

     }

     int maxc = min( siz[u], m );

     for( int c=; c<=maxc; c++ )

         pp[c] = -oo;

     pp[] = ;

     for( int t=head[u]; t; t=next[t] ) {

         int v=dest[t], w=wght[t];

         if( v==fa ) continue;

         for( int c=maxc; c>=; c-- ) {

             int msc = min( c, siz[v] );

             for( int sc=; sc<=msc; sc++ ) {

                 dnt tv = pp[c-sc]+dp[v][sc]+((dnt)sc*(m-sc)+(siz[v]-sc)*(n-m-siz[v]+sc))*w;

                 pp[c] = max( pp[c], tv );

             }

         }

     }

     dp[u][] = pp[];

     for( int c=; c<=maxc; c++ )

         dp[u][c] = max( pp[c], pp[c-] );

 } 

 int main() {

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

     if( n-m<m ) m=n-m;

     for( int i=,u,v,w; i<n; i++ ) {

         scanf( "%d%d%d", &u, &v, &w );

         adde( u, v, w );

         adde( v, u, w );

     }

     dfs(,);

     printf( "%lld\n", dp[][m] );

 }