#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
/*
t[j] - t[i] >= abs(a[i] - a[j])
t[j] - t[i] >= a[i] - a[j] and t[j] - t[i] >= a[j] - a[i]
t[j] + a[j] >= t[i] + a[i] and t[j] - a[j] >= t[i] - a[i]
*/
const int M = 5e5 + 25;
int n, m;
array <ll, 2> a[M];
int vis[M];
void solve () {
cin >> n >> m;
for (int i = 1; i <= m; i++) {
cin >> a[i][0];
}
for (int i = 1; i <= m; i++) {
cin >> a[i][1];
}
sort(a + 1, a + m + 1);
for (int i = 1; i <= m; i++) {
a[i] = {a[i][0] - a[i][1], a[i][0] + a[i][1]};
}
sort(a + 1, a + m + 1);
vector <int> c;
for (int i = 1; i <= m; i++) {
c.push_back(a[i][1]);
}
set <int> ee;
for (auto i : c) {
auto g = ee.lower_bound(i + 1);
if (g == ee.begin()) {
ee.insert(i);
} else {
g--;
ee.erase(g);
ee.insert(i);
}
}
cout << (int)ee.size() << '\n';
}
signed main () {
ios::sync_with_stdio(0); cin.tie(0);
int tc = 1; //cin >> tc;
while (tc--) solve();
}
