#include <bits/stdc++.h>
using namespace std;
inline long long gi() {
  register long long data = 0, fu = 1;
  register char ch = getchar();
  while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();
  if (ch == '-') fu = -1, ch = getchar();
  while ('0' <= ch && ch <= '9')
    data = (data << 1) + (data << 3) + (ch ^ 48), ch = getchar();
  return fu * data;
}
const long long inf = 1e16;
int stk[200005], nxt[200005], n, K;
long long pre[200005], suf[200005], W[200005], g[200005], root;
int Ans;
vector<int> edge[200005];
namespace Seg {
long long Minp[200005 << 2], Maxs[200005 << 2], ans[200005 << 2],
    tag[200005 << 2];
inline void Add(int o, long long v) {
  Maxs[o] += v;
  tag[o] += v;
  ans[o] += v;
  return;
}
inline void PushDown(int o) {
  if (tag[o] == 0) return;
  Add(o << 1, tag[o]);
  Add(o << 1 | 1, tag[o]);
  tag[o] = 0;
}
long long Calc(int o, int l, int r, long long x) {
  if (l == r) return x + Minp[o];
  int mid = (l + r) >> 1;
  PushDown(o);
  long long y = Maxs[o << 1];
  if (x >= y)
    return min(x + Minp[o << 1], Calc(o << 1 | 1, mid + 1, r, x));
  else
    return min(ans[o], Calc(o << 1, l, mid, x));
}
inline void PushUp(int o, int l, int r) {
  Maxs[o] = max(Maxs[o << 1], Maxs[o << 1 | 1]);
  int mid = (l + r) >> 1;
  ans[o] = Calc(o << 1 | 1, mid + 1, r, Maxs[o << 1]);
}
void Build(int o, int l, int r) {
  if (l == r) {
    Minp[o] = -suf[l];
    Maxs[o] = suf[l];
    ans[o] = 0;
    return;
  }
  int mid = (l + r) >> 1;
  Build(o << 1, l, mid);
  Build(o << 1 | 1, mid + 1, r);
  PushUp(o, l, r);
  Minp[o] = min(Minp[o << 1], Minp[o << 1 | 1]);
}
inline void Insert(int o, int l, int r, int ql, int qr, long long v) {
  if (ql <= l && r <= qr) {
    Add(o, v);
    return;
  }
  int mid = (l + r) >> 1;
  PushDown(o);
  if (ql <= mid) Insert(o << 1, l, mid, ql, qr, v);
  if (qr > mid) Insert(o << 1 | 1, mid + 1, r, ql, qr, v);
  PushUp(o, l, r);
}
int Solve(int o, int l, int r, long long x) {
  if (l == r) return x + Minp[o] <= K ? l : 0;
  int mid = (l + r) >> 1;
  PushDown(o);
  if (x + Minp[o << 1 | 1] <= K)
    return Solve(o << 1 | 1, mid + 1, r, x);
  else
    return Solve(o << 1, l, mid, x);
}
int Query(int o, int l, int r, long long x) {
  if (l == r) {
    return x + Minp[o] <= K ? l : 0;
  }
  int mid = (l + r) >> 1;
  PushDown(o);
  long long y = Maxs[o << 1];
  int ret = 0;
  if (x >= y) {
    ret = Query(o << 1 | 1, mid + 1, r, x);
    if (x + Minp[o] <= K) ret = max(ret, Solve(o << 1, l, mid, x));
  } else if (x <= y) {
    if (ans[o] <= K)
      ret = Query(o << 1 | 1, mid + 1, r, y);
    else
      ret = Query(o << 1, l, mid, x);
  }
  return ret;
}
}  // namespace Seg
inline void Pre() {
  stk[0] = 0;
  for (int i = n; i >= 1; i--) {
    while (stk[0] && pre[i - 1] <= pre[stk[stk[0]] - 1]) --stk[0];
    nxt[i] = stk[0] ? stk[stk[0]] : n + 1;
    stk[++stk[0]] = i;
  }
  root = n + 1;
  nxt[root] = n + 1;
  for (int i = 1; i <= n; i++) edge[nxt[i]].push_back(i);
  return;
}
inline int Bipart(int x) {
  int l = 2, r = stk[0], ret = 1;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if (pre[x - 1] - pre[stk[mid] - 1] <= K)
      ret = mid, r = mid - 1;
    else
      l = mid + 1;
  }
  return stk[ret - 1] - 1;
}
void Dfs(int u, int From) {
  stk[++stk[0]] = u;
  if (nxt[u] <= n)
    Seg::Insert(1, 1, n, nxt[u] - 1, n, pre[u - 1] - pre[nxt[u] - 1]);
  if (u <= n) {
    int r = Bipart(u);
    if (r < n) Seg::Insert(1, 1, n, r, n, inf);
    if (u != 1) Seg::Insert(1, 1, n, 1, u - 1, -inf);
    Ans = max(Ans, Seg::Query(1, 1, n, -inf) - u + 1);
    if (r < n) Seg::Insert(1, 1, n, r, n, -inf);
    if (u != 1) Seg::Insert(1, 1, n, 1, u - 1, inf);
  }
  for (auto v : edge[u])
    if (v != From) Dfs(v, u);
  --stk[0];
  if (nxt[u] <= n)
    Seg::Insert(1, 1, n, nxt[u] - 1, n, pre[nxt[u] - 1] - pre[u - 1]);
}
int main() {
  n = gi();
  K = gi();
  for (int i = 1; i < n; i++) W[i] = gi();
  W[n] = inf;
  for (int i = 1; i <= n; i++) g[i] = gi();
  for (int i = 1; i <= n; i++) pre[i] = pre[i - 1] + g[i] - W[i];
  for (int i = 1; i <= n; i++) suf[i] = suf[i - 1] + g[i] - W[i - 1];
  Pre();
  Seg::Build(1, 1, n);
  stk[0] = 0;
  Dfs(root, 0);
  cout << Ans << endl;
  return 0;
}
