#pragma GCC target ("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using H = pair<ll, ll>;
using P = pair<ll, H>;
using vi = vector<ll>;
#define all(a) (a).begin(),(a).end()
#define fs first
#define sc second
#define xx first
#define yy second.first
#define zz second.second
#define Q(i,j,k) mkp(i,mkp(j,k))
#define rng(i,s,n) for(ll i = (s) ; i < (n) ; i++)
#define rep(i,n) rng(i, 0, (n))
#define mkp make_pair
#define vec vector
#define pb emplace_back
#define siz(a) (int)(a).size()
#define crdcomp(b) sort(all((b)));(b).erase(unique(all((b))),(b).end())
#define getidx(b,i) (lower_bound(all(b),(i))-(b).begin())
#define ssp(i,n) (i==(ll)(n)-1?"\n":" ")
#define ctoi(c) (int)(c-'0')
#define itoc(c) (char)(c+'0')
#define cyes printf("Yes\n")
#define cno printf("No\n")
#define cdf(n) for(int quetimes_=(n);quetimes_>0;quetimes_--)
#define gcj printf("Case #%lld: ",qq123_+1)
#define readv(a,n) a.resize(n,0);rep(i,(n)) a[i]=read()
#define found(a,x) (a.find(x)!=a.end())
constexpr ll mod = (ll)1e9 + 7;
constexpr ll Mod = 998244353;
constexpr ld EPS = 1e-10;
constexpr ll inf = (ll)3 * 1e18;
constexpr int Inf = (ll)15 * 1e8;
constexpr int dx[] = { -1,1,0,0 }, dy[] = { 0,0,-1,1 };
template<class T>bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }
ll read() { ll u, k = scanf("%lld", &u); return u; }
string reads() { string s; cin >> s; return s; }
H readh(short g = 0) { H u; int k = scanf("%lld %lld", &u.fs, &u.sc); if (g == 1) u.fs--, u.sc--; if (g == 2) u.fs--; return u; }
bool ina(H t, int h, int w) { return 0 <= t.fs && t.fs < h && 0 <= t.sc && t.sc < w; }
bool ina(int t, int l, int r) { return l <= t && t < r; }
ll gcd(ll i, ll j) { return j ? gcd(j, i % j) : i; }
ll popcount(ll x) {
    int sum = 0; for (int i = 0; i < 60; i++)if ((1ll << i) & x) sum++;
    return sum;
}
template<typename T>
class csum {
    vec<T> v;
public:
    csum(vec<T>& a) :v(a) { build(); }
    csum() {}
    void init(vec<T>& a) { v = a; build(); }
    void build() {
        for (int i = 1; i < v.size(); i++) v[i] += v[i - 1];
    }
    //[l,r]
    T a(int l, int r) {
        if (r < l) return 0;
        return v[r] - (l == 0 ? 0 : v[l - 1]);
    }
    //[l,r)
    T b(int l, int r) {
        return a(l, r - 1);
    }
    T a(pair<int, int>t) {
        return a(t.first, t.second);
    }
    T b(pair<int, int>t) {
        return b(t.first, t.second);
    }
};
//--------------------------------------------------------------
template<typename T>
class sptable {
    vector<T>a; vector<int>log;
    vector<vector<int>>table;
    int n;
    using F = function<T(T, T)>;
    F func;
public:
    sptable() {}
    sptable(vector<T>& b, F comp) :a(b), n(b.size()), func(comp) {
        log.resize(n + 1);
        for (int i = 2; i <= n; i++) log[i] = log[i >> 1] + 1;

        table.assign(log[n] + 1, vector<int>(n));

        for (int i = 0; i < n; i++) table[0][i] = i;

        for (int k = 1; (1 << k) <= n; k++) {
            for (int i = 0; i + (1 << k) <= n; i++) {
                int c = table[k - 1][i];
                int d = table[k - 1][i + (1 << (k - 1))];
                if (func(a[c], a[d]) == a[c]) table[k][i] = c;
                else table[k][i] = d;
            }
        }
    }
    template<typename Iterator>
    sptable(const Iterator a, const Iterator b, F comp) {
        vector<T>c;
        for (auto k = a; k != b; k++) {
            c.push_back(*k);
        }
        *this = sptable(c, comp);
    }
    //[s,t)
    int query(int s, int t) {
        t--;
        int d = t - s + 1, k = log[d];
        if (func(a[table[k][s]], a[table[k][t - (1 << k) + 1]]) == a[table[k][s]])
            return table[k][s];
        else return table[k][t - (1 << k) + 1];
    }
    T num(int s, int t) {
        return a[query(s, t)];
    }
};
class LCA {
    using H = pair<int, ll>;
    int n;
    vector<H>e[300000];
    vector<int>ord, depth, id;
    vector<ll>dit;
    sptable<int> st;
    void dfs(int x, int p, int d, ll dis) {
        id[x] = (int)ord.size();
        ord.push_back(x);
        depth[x] = d;
        dit[x] = dis;
        for (H v : e[x]) {
            if (v.first != p) {
                dfs(v.first, x, d + 1, dis + v.second);
                ord.push_back(x);
            }
        }
    }
public:
    void init(int size) {
        n = size + 1;
        for (int i = 0; i < n; i++) e[i].clear();
        ord.clear(); depth.clear(); id.clear(); dit.clear();
        depth.resize(n); id.assign(n, -1);
    }
    void add_edge(int u, int v) {
        add_edge(u, v, 1);
    }
    void add_edge(int u, int v, ll r) {
        e[u].push_back(H{ v,r });
        e[v].push_back(H{ u,r });
    }
    void build(int root = 0) {
        dit.resize(n);
        depth.resize(n);
        id.resize(n);
        ord.reserve(2 * n - 1);
        dfs(root, -1, 0, 0);
        for (int i = 0; i < n; i++) {
            if (id[i] < 0) dfs(i, -1, 0, 0);
        }
        vector<int>stvec((int)ord.size());
        for (int i = 0; i < (int)ord.size(); i++) {
            stvec[i] = depth[ord[i]];
        }
        st = sptable<int>(stvec, [](int a, int b) {return min(a, b); });
    }
    int get(int u, int v) {
        return ord[st.query(min(id[u], id[v]), max(id[u], id[v]) + 1)];
    }
    ll dist(int u, int v) {
        int l = get(u, v);
        return dit[u] + dit[v] - 2 * dit[l];
    }
    int operator[](int x) {
        return depth[x];
    }
};
class BIT {
    int size;
    vector<int>dat;
public:
    BIT() {}
    BIT(int n) { init(n); }
    void init(int n) {
        size = n;
        dat.clear();
        dat.assign(size + 1, 0);
    }
    void add(int i, int x) {
        i++;
        while (i <= size) {
            dat[i] += x;
            i += i & -i;
        }
    }//0-indexed
    void add(int l, int r, int x) {
        add(l, x); add(r, -x);
    }//[l,r)
    int query(int i) {
        i++;
        int sum = 0;
        while (i > 0) {
            sum += dat[i];
            i -= i & -i;
        }
        return sum;
    }//0-indexed
    int query(int l, int r) {
        return query(r - 1) - query(l - 1);
    }//[l,r)
};//size, 0-indexed
//---------------------------------------------------------------------

int n, k;
vi a, b;
vec<H>e;
vec<int>f[200000];
vec<int>shn[200000];
LCA lca;
void generate() {
        n = read(), k = read();
        rep(i, k)a.pb(read() - 1);
        rep(i, k) b.pb(read());
        rep(i, n - 1) {
            e.pb(readh(1));
            f[e[i].fs].pb(e[i].sc);
            f[e[i].sc].pb(e[i].fs);
        }
}

ll solve() {
    lca.init(n);
    rep(i, n - 1) lca.add_edge(e[i].fs, e[i].sc);
    rep(i, k) shn[a[i]].pb(i);
    lca.build(0);
    ll ttt = 0;
    rep(i, k) ttt += abs(b[i]);

    vi pa(n, -1);
    rep(i, n) {
        for (int g : f[i]) {
            if (lca[g] == lca[i] - 1)
                pa[i] = g;
        }
    }
    csum<ll> lb(b);
    ll num = ll(k * ll(k + 1) / 2 + 2) / 2;
    ll ok = ttt + n, ng = -ttt - n, mid;

    while (ok - ng > 1) {
        mid = (ok + ng) / 2;

        auto F = [&](ll num) ->ll {
            ll sum = 1, r = 0; int t = a[k - 1];
            for (int i = k - 1; i >= 0; i--) {
                t = lca.get(t, a[i]);
                r += b[i];
                if (lca[t] + r <= num) sum++;
            }
            int pre = -1;
            int cnt = 0;
            vec<bool>c(k, 0);
            auto dfs = [&](int x, int p, auto dfs) ->void {
                for (auto g : shn[x]) c[g] = 1, cnt++;
                for (auto g : f[x]) {
                    if (g != p && g != pre) dfs(g, x, dfs);
                }
            };
            vi lf = { 0 }, rg = { 0 };
            r = 0;
            rep(i, k) {
                r += b[i];
                lf.pb(r);
            }
            r = 0;
            for (int i = k - 1; i >= 0; i--) {
                r += b[i];
                rg.pb(r);
            }
            crdcomp(lf); crdcomp(rg);
            BIT left(siz(lf)); 
            BIT right(siz(rg));
            right.add(getidx(rg, 0), 1);

            int l = 0; r = k - 1;//[0,l), [r+1, k)

            for (int cur = a[0]; ~cur; cur = pa[cur]) {
                dfs(cur, pa[cur], dfs);
                if (cnt == k) {
                    right.init(siz(rg)); //希望の地、楽園の跡、値さんです
                    right.add(getidx(rg, 0), 1);
                    for (int i = k - 2; i >= l; i--) {
                        sum += right.query(upper_bound(all(rg), num - lb.a(0, i) - lca[cur]) - rg.begin() - 1);

                        right.add(getidx(rg, lb.b(i + 1, k)), 1);
                    }

                    left.init(siz(lf));
                    for (int i = 1; i <= r; i++) {
                        sum += left.query(upper_bound(all(lf), num - lb.a(i, k - 1) - lca[cur]) - lf.begin() - 1);

                        if (i - 1 < l)left.add(getidx(lf, lb.a(0, i - 1)), 1);
                    }
                    break;
                }

                else {
                    while (c[l]) {
                        sum += right.query(upper_bound(all(rg), num - lb.a(0, l) - lca[cur]) - rg.begin() - 1);
                        left.add(getidx(lf, lb.a(0, l)), 1);
                        l++;
                    }
                    while (c[r]) {
                        sum += left.query(upper_bound(all(lf), num - lb.a(r, k - 1) - lca[cur]) - lf.begin() - 1);
                        right.add(getidx(rg, lb.b(r, k)), 1);
                        r--;
                    }
                }
                pre = cur;
            }
            return sum;
        };
        if (F(mid) >= num) ok = mid;
        else ng = mid;
    }
    return ok;
}

signed main() {
    generate();
    ll ans = solve();
    cout << ans << endl;
}