#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF (int)1e18
#define f first
#define s second
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
int n, m;
const int maxn = 5e5 + 69;
int lis(vector<int> a) {
vector<int> d(n+1, INF);
d[0] = -INF;
for (int i = 0; i < n; i++) {
int l = upper_bound(d.begin(), d.end(), a[i]) - d.begin();
if (d[l-1] < a[i] && a[i] < d[l])
d[l] = a[i];
}
int ans = 0;
for (int l = 0; l <= n; l++) {
if (d[l] < INF)
ans = l;
}
return ans;
}
void Solve()
{
cin>>m>>n;
pair <int, int> a[maxn];
for (int i=1; i<=n; i++){
int x; cin>>x;
a[i].f += x;
a[i].s -= x;
}
for (int i=1; i<=n; i++){
int x; cin>>x;
a[i].f += x;
a[i].s += x;
a[i].s = -a[i].s;
}
sort(a+1, a+n+1);
vector <int> v;
for (int i=1; i<=n; i++){
v.push_back(-a[i].s);
}
// for (auto x: v)
// cout<<x<<" ";
cout<<lis(v)<<"\n";
}
int32_t main()
{
auto begin = std::chrono::high_resolution_clock::now();
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
//cin >> t;
for(int i = 1; i <= t; i++)
{
//cout << "Case #" << i << ": ";
Solve();
}
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
return 0;
}
