using System;
using System.IO;
using System.Linq;

using ll = System.Int64;

class vinh
{
    static void uia()
    {
        int n = uiia.cin();
        if(n == 0) return;
        int k = uiia.cin();

        ll[] a = new ll[n + 1];
        for(int i = 1; i <= n; i++){
            a[i] = uiia.nl();
        }

        int[] head = new int[n + 1];
        int[] to = new int[2 * n + 5];
        ll[] we = new ll[2 * n + 5];
        int[] next = new int[2 * n + 5];
        int cd = 1;

        for(int i = 1; i < n; i++){
            int u = uiia.cin();
            int v = uiia.cin();
            ll w = uiia.nl();

            to[cd] = v;
            we[cd] = w;
            next[cd] = head[u];
            head[u] = cd++;

            to[cd] = u;
            we[cd] = w;
            next[cd] = head[v];
            head[v] = cd++;
        }

        int[] bgb = new int[n + 1];
        int[] de = new int[n + 1];
        int dd = 0;

        int[] q = new int[n + 1];
        int h = 0, t = 0;

        q[t++] = 1;
        bgb[1] = 0;

        while(h < t){
            int u = q[h++];
            de[++dd] = u;
            for(int e = head[u]; e != 0; e = next[e]){
                int v = to[e];
                if(v != bgb[u]){
                    bgb[v] = u;
                    q[t++] = v;
                }
            }
        }

        ll[][] dp = new ll[n + 1][];
        int[] sz = new int[n + 1];

        for(int id = n; id >= 1; id--){
            int u = de[id];
            sz[u] = 1;
            dp[u] = new ll[2];
            dp[u][0] = 0;
            dp[u][1] = a[u];

            for(int e = head[u]; e != 0; e = next[e]){
                int v = to[e];
                if(v == bgb[u]) continue;

                int lu = Math.Min(k, sz[u]);
                int lv = Math.Min(k, sz[v]);
                int ns = Math.Min(k, sz[u] + sz[v]);

                ll[] ndp = new ll[ns + 1];
                for(int i = 0; i <= ns; i++) ndp[i] = -1000000000000000000L;

                ll w = we[e];

                for(int i = 0; i <= lu; i++){
                    if(dp[u][i] <= -500000000000000000L) continue;
                    for(int j = 0; j <= lv; j++){
                        if(i + j > k) break;
                        if(dp[v][j] <= -500000000000000000L) continue;

                        ll c = dp[u][i] + dp[v][j];
                        if(j > 0 && j < k) c -= w;

                        if(c > ndp[i + j]) ndp[i + j] = c;
                    }
                }
                dp[u] = ndp;
                sz[u] = ns;
            }
        }

        uiia.coutl(dp[1][k]);
    }

    static void LOVE(string s)
    {
        if(File.Exists(s + ".inp"))
        {
            uiia.r = new FileStream(s + ".inp", FileMode.Open, FileAccess.Read);
            uiia.w = new StreamWriter(new FileStream(s + ".out", FileMode.Create, FileAccess.Write), System.Text.Encoding.ASCII, 65536);
        }
        else if(File.Exists("input.txt"))
        {
            uiia.r = new FileStream("input.txt", FileMode.Open, FileAccess.Read);
        }
    }

    static void Main()
    {
        uiia.init();
        LOVE("HIV à?");
        int t = 1;
        
        while(t-- > 0) uia();
        uiia.flush();
    }
}

public static class uiia
{
    public static Stream r; public static StreamWriter w;
    static byte[] buf = new byte[65536]; static int id = 0, cnt = 0;
    public static void init() { r = Console.OpenStandardInput(); w = new StreamWriter(Console.OpenStandardOutput(), System.Text.Encoding.ASCII, 65536); }
    static int Read() { if(id >= cnt) { id = 0; cnt = r.Read(buf, 0, 65536); if(cnt == 0) return -1; } return buf[id++]; }
    public static string next() {
        int c = Read(); while(c <= 32) { if(c == -1) return null; c = Read(); }
        var sb = new System.Text.StringBuilder();
        while(c > 32) { sb.Append((char)c); c = Read(); }
        return sb.ToString();
    }
    public static int cin() =>(int)nl();
    public static ll nl() {
        int c = Read(); while(c <= 32) { if(c == -1) return 0; c = Read(); }
        bool neg = false; if(c == '-') { neg = true; c = Read(); }
        ll res = 0; while(c > 32) { res = res * 10 + c - '0'; c = Read(); }
        return neg ? -res : res;
    }
    public static void cout(object o) => w.Write(o);
    public static void coutl(object o) => w.WriteLine(o);
    public static void flush() => w.Flush();
}