#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
inline T1 max(T1 a, T2 b) {
  return b < a ? a : b;
}
template <typename T1, typename T2>
inline T1 min(T1 a, T2 b) {
  return a < b ? a : b;
}
namespace ae86 {
const int bufl = 1 << 15;
char buf[bufl], *s = buf, *t = buf;
inline int fetch() {
  if (s == t) {
    t = (s = buf) + fread(buf, 1, bufl, stdin);
    if (s == t) return EOF;
  }
  return *s++;
}
inline long long ty() {
  long long a = 0;
  int b = 1, c = fetch();
  while (!isdigit(c)) b ^= c == '-', c = fetch();
  while (isdigit(c)) a = a * 10 + c - 48, c = fetch();
  return b ? a : -a;
}
}  // namespace ae86
using ae86::ty;
const int _ = 300007;
const long long linf = 1e16;
long long lim, w[_], g[_], sgl[_] = {0}, sgr[_] = {0};
struct sgt {
  static const int _t = _ << 2;
  long long mip[_t], mxs[_t];
  long long ans[_t], tadd[_t];
  inline void putadd(int x, long long dlt) {
    mxs[x] += dlt, ans[x] += dlt, tadd[x] += dlt;
  }
  inline void dwn(int x) {
    if (tadd[x])
      putadd((x << 1), tadd[x]), putadd((x << 1 | 1), tadd[x]), tadd[x] = 0;
  }
  long long findans(int x, int l, int r, long long mxl) {
    if (l == r) return mip[x] + mxl;
    dwn(x);
    if (mxl <= mxs[(x << 1)])
      return min(findans((x << 1), l, ((l + r) >> 1), mxl), ans[x]);
    return min(mip[(x << 1)] + mxl,
               findans((x << 1 | 1), ((l + r) >> 1) + 1, r, mxl));
  }
  inline void up(int x, int l, int r) {
    mip[x] = min(mip[(x << 1)], mip[(x << 1 | 1)]);
    mxs[x] = max(mxs[(x << 1)], mxs[(x << 1 | 1)]);
    ans[x] = findans((x << 1 | 1), ((l + r) >> 1) + 1, r, mxs[(x << 1)]);
  }
  void plant(int x, int l, int r) {
    if (l == r) {
      mip[x] = -sgr[l], mxs[x] = sgr[l];
      return;
    }
    plant((x << 1), l, ((l + r) >> 1)),
        plant((x << 1 | 1), ((l + r) >> 1) + 1, r), up(x, l, r);
  }
  void change(int x, int l, int r, int tl, int tr, long long dlt) {
    if (tl <= l && r <= tr) {
      putadd(x, dlt);
      return;
    }
    dwn(x);
    if (tl <= ((l + r) >> 1)) change((x << 1), l, ((l + r) >> 1), tl, tr, dlt);
    if (tr > ((l + r) >> 1))
      change((x << 1 | 1), ((l + r) >> 1) + 1, r, tl, tr, dlt);
    up(x, l, r);
  }
  long long query(int x, int l, int r, long long mxl) {
    if (l == r) return (mxl + mip[x] <= lim) ? l : 0;
    dwn(x);
    if (mip[(x << 1 | 1)] + mxl <= lim)
      return query((x << 1 | 1), ((l + r) >> 1) + 1, r, mxl);
    return query((x << 1), l, ((l + r) >> 1), mxl);
  }
  long long finder(int x, int l, int r, long long mxl) {
    if (l == r) return (mxl + mip[x] <= lim) ? l : 0;
    dwn(x);
    if (mxs[(x << 1)] >= mxl) {
      if (ans[x] <= lim)
        return finder((x << 1 | 1), ((l + r) >> 1) + 1, r, mxs[(x << 1)]);
      return finder((x << 1), l, ((l + r) >> 1), mxl);
    }
    return max(query((x << 1), l, ((l + r) >> 1), mxl),
               finder((x << 1 | 1), ((l + r) >> 1) + 1, r, mxl));
  }
} t;
int n, stk[_], top = 0, nex[_], ans = 1;
vector<int> e[_];
void dfs(int x) {
  stk[++top] = x;
  if (x != n + 1) {
    if (x > 1) t.change(1, 1, n, 1, x - 1, -linf);
    t.change(1, 1, n, nex[x] - 1, n, sgl[x - 1] - sgl[nex[x] - 1]);
    int l = 1, r = top, loc = top;
    while (r >= l) {
      int mid = (l + r) >> 1;
      if (sgl[x - 1] - sgl[stk[mid] - 1] <= lim)
        loc = mid, r = mid - 1;
      else
        l = mid + 1;
    }
    loc = stk[loc - 1];
    if (loc <= n) t.change(1, 1, n, loc, n, linf);
    ans = max(ans, t.finder(1, 1, n, -linf) - x + 1);
    if (loc <= n) t.change(1, 1, n, loc, n, -linf);
    if (x > 1) t.change(1, 1, n, 1, x - 1, linf);
  }
  for (auto b : e[x]) dfs(b);
  if (x != n + 1)
    t.change(1, 1, n, nex[x] - 1, n, sgl[nex[x] - 1] - sgl[x - 1]);
  top--;
}
int main() {
  n = ty(), lim = ty();
  for (int i = 1; i < n; i++) w[i] = ty();
  for (int i = 1; i <= n; i++) g[i] = ty();
  w[n] = linf;
  for (int i = 1; i <= n; i++)
    sgl[i] = sgl[i - 1] + g[i] - w[i], sgr[i] = sgr[i - 1] + g[i] - w[i - 1];
  stk[++top] = n;
  for (int i = n - 1; i >= 0; i--) {
    while (top >= 1 && sgl[stk[top]] >= sgl[i]) top--;
    nex[i + 1] = stk[top] + 1, e[nex[i + 1]].push_back(i + 1);
    stk[++top] = i;
  }
  t.plant(1, 1, n);
  top = 0, dfs(n + 1);
  printf("%d\n", ans);
  return 0;
}
