#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb push_back
vector<int> t, a;
vector<pair<int, int>> bf, nrm;
set<int> max_cresc;
int main () {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, i, b, f, val, idx;
cin >> n >> m;
t = vector<int>(m + 1);
for (i = 1; i <= m; i++) {
cin >> t[i];
}
a = vector<int>(m + 1);
bf = vector<pair<int, int>>(m + 1);
for (i = 1; i <= m; i++) {
cin >> a[i];
f = t[i] - a[i];
b = t[i] + a[i];
bf[i] = make_pair(f, b);
}
sort(bf.begin() + 1, bf.end());
nrm = vector<pair<int, int>>(m + 1);
for (i = 1; i <= m; i++) {
val = bf[i].second;
idx = i;
nrm[i] = make_pair(val, idx);
}
sort(nrm.begin() + 1, nrm.end());
for (i = 1; i <= m; i++) {
auto it = max_cresc.lower_bound(nrm[i].second);
if (it == max_cresc.begin()) {
max_cresc.insert(nrm[i].second);
continue;
}
max_cresc.erase(prev(it));
max_cresc.insert(nrm[i].second);
}
cout << max_cresc.size() << "\n";
return 0;
}
