#include <bits/stdc++.h>
using namespace std;
int cc[100002];
pair<int, int> in[100002];
vector<pair<int, int> > adj[100002];
int pos = 1;
int l[100002], r[100002], label[100002];
long long d[100002];
void dfs(int node, int par, long long depth = 0) {
  l[node] = pos;
  d[node] = depth;
  int ch, w;
  for (pair<int, int> edge : adj[node]) {
    if (edge.first == par) {
      continue;
    }
    dfs(edge.first, node, depth + edge.second);
  }
  label[pos] = node;
  r[node] = pos++;
}
long long pen[100002];
void update(int ind, long long add) {
  while (ind < 100002) {
    pen[ind] += add;
    ind += ind & (-ind);
  }
}
long long query(int ind) {
  long long ret = 0;
  while (ind > 0) {
    ret = ret + pen[ind];
    ind = ind & (ind - 1);
  }
  return ret;
}
pair<long long, int> seg[100002 * 4];
long long lazy[100002 * 4];
const long long inf = -4e18;
void init(int pos, int l, int r) {
  lazy[pos] = 0;
  if (l == r) {
    seg[pos] = {d[label[l]], l};
    return;
  }
  int mid = (l + r) / 2;
  init(pos * 2, l, mid);
  init(pos * 2 + 1, mid + 1, r);
  seg[pos] = max(seg[pos * 2], seg[pos * 2 + 1]);
}
void push(int pos, int l, int r) {
  if (lazy[pos] != 0) {
    seg[pos].first += lazy[pos];
    if (l != r) {
      lazy[pos * 2] += lazy[pos];
      lazy[pos * 2 + 1] += lazy[pos];
    }
    lazy[pos] = 0;
  }
}
void update(int pos, int l, int r, int ql, int qr, long long val) {
  push(pos, l, r);
  if (r < ql || qr < l) {
    return;
  }
  if (ql <= l && r <= qr) {
    lazy[pos] = val;
    push(pos, l, r);
    return;
  }
  int mid = (l + r) / 2;
  update(pos * 2, l, mid, ql, qr, val);
  update(pos * 2 + 1, mid + 1, r, ql, qr, val);
  seg[pos] = max(seg[pos * 2], seg[pos * 2 + 1]);
}
pair<long long, int> query(int pos, int l, int r, int ql, int qr) {
  push(pos, l, r);
  if (r < ql || qr < l) {
    return {inf, 0};
  }
  if (ql <= l && r <= qr) {
    return seg[pos];
  }
  int mid = (l + r) / 2;
  return max(query(pos * 2, l, mid, ql, qr),
             query(pos * 2 + 1, mid + 1, r, ql, qr));
}
long long w[100002];
long long dfs2(int node, int par) {
  priority_queue<long long> pq;
  for (pair<int, int> edge : adj[node]) {
    if (edge.first == par) {
      continue;
    }
    pq.push(dfs2(edge.first, node));
  }
  long long ret = w[node];
  if (node != 1) {
    if (pq.size() > 0) pq.pop();
  }
  if (pq.size() > 0) {
    ret = max(ret, pq.top());
  }
  return ret;
}
void solve() {
  int n;
  long long T;
  scanf("%d %lld ", &n, &T);
  long long rb = 0;
  for (int i = 1; i <= n; ++i) {
    scanf("%d  ", &cc[i]);
    rb += cc[i];
  }
  for (int i = 1; i <= n; ++i) {
    scanf("%d ", &in[i].first);
    in[i].second = i;
  }
  sort(in + 1, in + n + 1);
  for (int i = 2; i <= n; ++i) {
    int p, l;
    scanf("%d %d ", &p, &l);
    l *= 2;
    adj[p].push_back({i, l});
  }
  dfs(1, 0);
  init(1, 1, n);
  for (int i = 1; i <= n; ++i) {
    int node, co, p, x, y;
    node = in[i].second;
    co = cc[node];
    p = r[node];
    x = l[node], y = p;
    long long val = (long long)co * in[i].first;
    while (true) {
      pair<long long, int> q = query(1, 1, n, x, y);
      if (q.first + val >= T) {
        long long remCC = min((T - q.first) / in[i].first, (long long)co);
        w[label[q.second]] = query(q.second) + remCC;
        update(1, 1, n, q.second, q.second, inf);
      } else {
        break;
      }
    }
    update(1, 1, n, x, y, val);
    update(x, co);
    update(y + 1, -co);
  }
  while (true) {
    pair<long long, int> q = query(1, 1, n, 1, n);
    if (q.first < 0) {
      break;
    }
    w[label[q.second]] = query(q.second);
    update(1, 1, n, q.second, q.second, inf);
  }
  printf("%lld\n", dfs2(1, 0));
}
int main() {
  solve();
  return 0;
}
