#include <iostream>

#include <cstring>

#include <cstdio>

#include <vector>

#include <set>

#define fi first

#define se second

using namespace std;

const int maxn = 1e6 + ;

typedef pair<long long, int> PLI;

typedef pair<int, long long> PIL;

vector<PIL> G[maxn];int sz[maxn], k;

long long ans = ;

void dfs(int x, int fa){

    sz[x] = ;

    for(auto e : G[x]){

        if(e.fi == fa) continue;

        dfs(e.fi, x);

        sz[x] += sz[e.fi];

        ans += min(k, sz[e.fi])*e.se;

    }

}

int main()

{

    int x, y, v, n;

    while(cin>>n>>k){

        ans = ;

        for(int i = ; i <= n; i++) G[i].clear();

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

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

            G[x].push_back({y, v});

            G[y].push_back({x, v});

        }

        dfs(, );

        cout<<ans<<endl;

    }

}