#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define flt double
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()

mt19937 rnd(234);
const ll inf = 1e18;

int n, k;
vector<ll> a;
vector<vector<int>> g;

void dfs0(int v, int p) {
    auto it = find(all(g[v]), p);
    if (it != g[v].end()) {
        g[v].erase(it);
    }
    for (auto to : g[v]) {
        dfs0(to, v);
    }
}

void dfs1(int v, ll sm, ll &rs) {
    sm += a[v];
    rs = max(rs, sm);
    for (auto to : g[v]) {
        dfs1(to, sm, rs);
    }
}

ll solve() {
    ll rs = 0;
    if (k == 1) {
        dfs1(0, 0, rs);
        return rs;
    }
    return -1;
}

int32_t main() {
    if (1) {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout.tie(0);
    }
    cin >> n >> k;
    g.assign(n, vector<int>());
    for (int i = 0; i < n - 1; i += 1) {
        int u, v;
        cin >> u >> v;
        --u;
        --v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    a.resize(n);
    for (int i = 0; i < n; i += 1) {
        cin >> a[i];
    }
    dfs0(0, -1);
    cout << solve() << "\n";
    return 0;
}