#include<bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define mp make_pair
using namespace std;
// #define fin cin
// #define fout cout
ifstream fin("haoi2015_t1.in");
ofstream fout("haoi2015_t1.out");
auto mread = [](){
    int x;
    fin >> x;
    return x;
};
const int N = 2005;
int n = mread(), k = mread(), f[N][N], siz[N];
vector<pair<int, int> > v[N];
void dfs(int x, int fa){
    siz[x] = 1;
    for(auto t : v[x]){
        int y = t.fi, w = t.se;
        if(y == fa){
            continue;
        }
        dfs(y, x);
        siz[x] += siz[y];
    }
    f[x][0] = f[x][1] = 0;
    for(auto t : v[x]){
        int y = t.fi, w = t.se;
        if(y == fa){
            continue;
        }
        for(int i = min(k, siz[x]); i >= 0; i --){
            for(int j = 0; j <= min(siz[y], i); j ++){
                f[x][i] = max(f[x][i], f[x][i - j] + f[y][j] + (j * (k - j) + (siz[y] - j) * ((n - k) - (siz[y] - j))) * w);
            }
        }
    }
    return;
}
signed main(){
    for(int i = 1, x, y, z; i < n; i ++){
        x = mread(), y = mread(), z = mread();
        v[x].push_back(mp(y, z));
        v[y].push_back(mp(x, z));
    }
    memset(f, -0x3f, sizeof(f));
    dfs(1, 0);
    fout << f[1][k];
    return 0;
}