#include <bits/stdc++.h> #pragma GCC optimize("O3") using namespace std; using ll = long long; #define int ll signed main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int n,m; cin >> n >> m; vector<int> t(m); for(int& i : t) cin >> i; vector<int> a(m); for(int& i : a) cin >> i; vector<int> u(m); for(int i = 0; i < m; i++) u[i] = a[i]+t[i]; vector<int> v(m); for(int i = 0; i < m; i++) v[i] = a[i]-t[i]; vector<pair<int,int>> seq(m); for(int i = 0; i < m; i++) seq[i] = {u[i],-v[i]}; sort(seq.begin(),seq.end()); vector<int> lis; for(auto& [u,mv] : seq) { auto itr = lower_bound(lis.begin(),lis.end(),mv); if(itr==lis.end()) lis.push_back(mv); else *itr = mv; } cout << lis.size() << "\n"; return 0; }