#ifndef LOCAL
#define FAST_IO
#endif
// ===== template.hpp =====
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#define OVERRIDE(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32) (n); ++i)
#define REP3(i, m, n) for (i32 i = (i32) (m); i < (i32) (n); ++i)
#define REP(...) OVERRIDE(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER(i, n) for (i32 i = (i32) (n) - 1; i >= 0; --i)
#define ALL(x) begin(x), end(x)
using namespace std;
using u32 = unsigned int;
using u64 = unsigned long long;
using u128 = __uint128_t;
using i32 = signed int;
using i64 = signed long long;
using i128 = __int128_t;
using f64 = double;
using f80 = long double;
template <typename T>
using Vec = vector<T>;
template <typename T>
bool chmin(T &x, const T &y) {
if (x > y) {
x = y;
return true;
}
return false;
}
template <typename T>
bool chmax(T &x, const T &y) {
if (x < y) {
x = y;
return true;
}
return false;
}
istream &operator>>(istream &is, i128 &x) {
i64 v;
is >> v;
x = v;
return is;
}
ostream &operator<<(ostream &os, i128 x) {
os << (i64) x;
return os;
}
istream &operator>>(istream &is, u128 &x) {
u64 v;
is >> v;
x = v;
return is;
}
ostream &operator<<(ostream &os, u128 x) {
os << (u64) x;
return os;
}
[[maybe_unused]] constexpr i32 INF = 1000000100;
[[maybe_unused]] constexpr i64 INF64 = 3000000000000000100;
struct SetUpIO {
SetUpIO() {
#ifdef FAST_IO
ios::sync_with_stdio(false);
cin.tie(nullptr);
#endif
cout << fixed << setprecision(15);
}
} set_up_io;
// ===== template.hpp =====
#ifdef DEBUGF
#include "cpl/template/debug.hpp"
#else
#define DBG(x) (void) 0
#endif
class RMaxQ {
i32 n;
Vec<i32> node;
public:
RMaxQ(i32 n) : n(n), node(2 * n, 0) {}
void update_max(i32 idx, i32 val) {
idx += n;
while (idx > 0) {
chmax(node[idx], val);
idx /= 2;
}
}
i32 range_max(i32 l, i32 r) const {
l += n;
r += n;
i32 ans = 0;
while (l < r) {
if (l % 2 == 1) {
chmax(ans, node[l++]);
}
if (r % 2 == 1) {
chmax(ans, node[--r]);
}
l /= 2;
r /= 2;
}
return ans;
}
};
i32 position(const Vec<i32> &xs, i32 x) {
return (i32) (lower_bound(ALL(xs), x) - xs.begin());
}
int main() {
i32 n, m;
cin >> n >> m;
Vec<i32> t(m), a(m);
REP(i, m) {
cin >> t[i];
}
REP(i, m) {
cin >> a[i];
}
Vec<pair<i32, i32>> evs(m);
REP(i, m) {
evs[i].first = a[i] - t[i];
evs[i].second = a[i] + t[i];
}
sort(ALL(evs));
Vec<i32> dp(m, 0);
REP(i, m) {
++dp[i];
REP(j, i + 1, m) {
if (evs[i].first < evs[j].first && evs[i].second < evs[j].second) {
chmax(dp[j], dp[i]);
}
}
}
cout << *max_element(ALL(dp)) << '\n';
}
