/*
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
*/
#include <bits/stdc++.h>
#define taskname ""
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define i64 long long
#define pb push_back
#define ff first
#define ss second
#define isz(x) (int)x.size()
using namespace std;
const int mxN = 5e5 + 5;
const int mod = 1e9 + 7;
const i64 oo = 1e18;
struct Button {
int pos, tm;
bool operator < (const Button &rhs) {
if (tm + pos == rhs.tm + rhs.pos) return tm - pos < rhs.tm - rhs.pos;
return tm + pos < rhs.tm + rhs.pos;
}
};
int n, m;
vector<Button> v;
void solve() {
cin >> n >> m;
v.resize(m + 1);
for (int i = 1; i <= m; ++i) cin >> v[i].tm;
for (int i = 1; i <= m; ++i) cin >> v[i].pos;
sort(v.begin() + 1, v.end());
set<int> s;
for (int i = 1; i <= m; ++i) {
int cur = v[i].tm - v[i].pos;
auto it = s.upper_bound(cur);
if (it != s.begin()) {
it = prev(it);
s.erase(it);
}
s.insert(cur);
}
cout << isz(s) << endl;
}
signed main() {
#ifndef CDuongg
if(fopen(taskname".inp", "r"))
assert(freopen(taskname".inp", "r", stdin)), assert(freopen(taskname".out", "w", stdout));
#else
freopen("bai3.inp", "r", stdin);
freopen("bai3.out", "w", stdout);
auto start = chrono::high_resolution_clock::now();
#endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1; //cin >> t;
while(t--) solve();
#ifdef CDuongg
// auto end = chrono::high_resolution_clock::now();
// cout << "\n"; for(int i = 1; i <= 100; ++i) cout << '=';
// cout << "\nExecution time: " << chrono::duration_cast<chrono::milliseconds> (end - start).count() << "[ms]" << endl;
// cout << "Check array size pls sir" << endl;
#endif
}
