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

     Problem: 4033

     User: rausen

     Language: C++

     Result: Accepted

     Time:308 ms

     Memory:32300 kb

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

 #include <cstdio>

 #include <cstring>

 #include <algorithm>

 using namespace std;

 typedef long long ll;

 const int N = 2e3 + ;

 struct edge {

     int next, to, v;

     edge(int _n = , int _t = , int _v = ) : next(_n), to(_t), v(_v) {}

 } e[N << ];

 int n, k;

 int first[N], tot;

 int sz[N];

 ll f[N][N], tmp[N];

 inline void Add_Edges(int x, int y, int z) {

     e[++tot] = edge(first[x], y, z), first[x] = tot;

     e[++tot] = edge(first[y], x, z), first[y] = tot;

 }

 inline ll calc(int x, int y) {

     return 1ll * y * (x - y);

 }

 #define y e[x].to

 inline void dfs(int p, int fa, int w) {

     int x, i, j;

     sz[p] = ;

     for (x = first[p]; x; x = e[x].next)

         if (y != fa) {

             dfs(y, p, e[x].v);

             memcpy(tmp, f[p], sizeof(tmp));

             for (i = min(sz[p], k); ~i; --i)

                 for (j = min(sz[y], k - i); ~j; --j)

                     tmp[i + j] = max(tmp[i + j], f[p][i] + f[y][j]);

             memcpy(f[p], tmp, sizeof(tmp));

             sz[p] += sz[y];

         }

     for (i = min(sz[p], k); ~i; --i)

         f[p][i] += (calc(k, i) + calc(n - k, sz[p] - i)) * w;

 }

 #undef y

 int main() {

     int i, x, y, z;

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

     for (i = ; i < n; ++i) {

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

         Add_Edges(x, y, z);

     }

     dfs(, , );

     printf("%lld\n", f[][k]);

     return ;

 }