#include <bits/stdc++.h>
using namespace std;
using lint = long long;
template<class T = int> using V = vector<T>;
template<class T = int> using VV = V< V<T> >;

int main() {
  cin.tie(nullptr); ios::sync_with_stdio(false);
  int n, k; cin >> n >> k, --k;
  V<lint> x(n); for (auto&& e : x) cin >> e;
  V<lint> a(n); for (auto&& e : a) cin >> e;
  VV<> g(2 * n);
  for (int i = 0; i < n; ++i) {
    int l = lower_bound(begin(x), end(x), x[i] - a[i]) - begin(x);
    int r = upper_bound(begin(x), end(x), x[i] + a[i]) - begin(x);
    l += n, r += n;
    while (l < r) {
      if (l & 1) {
        g[n + i].push_back(l++);
      }
      if (r & 1) {
        g[n + i].push_back(--r);
      }
      l >>= 1, r >>= 1;
    }
  }
  for (int i = 1; i < n; ++i) {
    g[i].push_back(2 * i);
    g[i].push_back(2 * i + 1);
  }
  int res = 0;
  bitset<200000> vis;
  auto dfs = [&](const auto& dfs, int v) -> void {
    vis[v] = true;
    res += v >= n;
    for (int w : g[v]) if (!vis[w]) {
      dfs(dfs, w);
    }
  };
  dfs(dfs, n + k);
  cout << res << '\n';
}