#include <bits/stdc++.h>
#pragma GCC optimize("O3", "Ofast")
#define int long long
#define ll long long
#define se second
#define fi first
#define pb push_back
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
using namespace std;
typedef pair<int,int> pii;
typedef pair<pii,pii> ipii;
const int MAXN = 3e5+10;
const int MAXA = 5e5+10;
const int SQRT = 450;
const ll INF = 1e18;
const int MOD = 1e9+7;
const int LOG = 60;
int sum(int a, int b){ return (a+MOD+b)%MOD; }
void chsum(int &a, int b){ a = sum(a,b); }
int mul(int a, int b){ return (a*b)%MOD; }
void chmul(int &a, int b){ a = mul(a,b); }
void chmn(auto &a, auto b){ a = min(a, b); }
void chmx(auto &a, auto b){ a = max(a, b); }
vector<int> dx = {0, 0, -1, 1};
vector<int> dy = {1, -1, 0, 0};
int x, n, a[MAXN], t[MAXN];
vector<pii> vec;
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>x>>n;
for(int i=1; i<=n; i++) cin>>t[i];
for(int i=1; i<=n; i++){
cin>> a[i];
vec.pb({a[i]-t[i], -a[i]-t[i]});
}
sort(vec.begin(), vec.end());
set<int> s;
for(auto [tim, idx] : vec){
idx = -idx;
auto it = s.lower_bound(idx);
if(it!=s.end()) s.erase(it);
s.insert(idx);
}
cout << s.size() << '\n';
}
