/* code by the cute ~~Dengdualang~~ PixelCat owo */
/* as cute as nacho neko (aka. my wife)! */
/* Nhade stay for a night here */
/* 183234 deng deng deng pixelcat oops */
/* (yang wang yesu)*2 */
/* ^ some weird stuff. nvm =w= */
// #pragma GCC optimize("O4,unroll-loops,no-stack-protector")
// #pragma GCC target("avx,avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,fma")
#include <bits/stdc++.h>
#define int LL //__int128
#define double long double
using namespace std;
using LL = long long;
using LLL = __int128_t;
using uLL = unsigned long long;
using pii = pair<int, int>;
#define For(i, a, b) for (int i = a; i <= b; i++)
#define Fors(i, a, b, s) for (int i = a; i <= b; i += s)
#define Forr(i, a, b) for (int i = a; i >= b; i--)
#define F first
#define S second
#define L(id) (id * 2 + 1)
#define R(id) (id * 2 + 2)
#define LO(x) (x & (-x))
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define sz(x) ((int)x.size())
#define mkp make_pair
// #define MOD (int)(998244353)
#define MOD (int)((LL)1e9 + 7)
#define INF (int)(4e18)
// #define INF 1e9
#define EPS (1e-6)
#ifdef NYAOWO
#include "library/debug.hpp"
inline void USACO(const string &s) {
cerr << "USACO: " << s << "\n";
}
#else
#define debug(...)
inline void timer() {}
inline void USACO(const string &s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
#endif
inline void NYA() {
ios::sync_with_stdio(false);
cin.tie(0);
}
inline int gcd(int a, int b) {
return __gcd(a, b);
}
inline int lcm(int a, int b) {
return a / gcd(a, b) * b;
}
int fpow(int b, int p, const int &mod) {
int ans = 1;
while (p) {
if (p & 1) ans = ans * b % mod;
p >>= 1;
b = b * b % mod;
}
return ans;
}
int fpow(int b, int p) {
return fpow(b, p, MOD);
}
template <typename T>
inline void chmin(T &_a, const T &_b) {
if (_b < _a) _a = _b;
}
template <typename T>
inline void chmax(T &_a, const T &_b) {
if (_b > _a) _a = _b;
}
// mt19937_64 rng(
// chrono::steady_clock::now().time_since_epoch().count());
int32_t main() {
// NYA();
// nyaacho >/////<
// miku sama bless me >/////<
int n,m; cin>>n>>m;
vector<pii> p(n);
vector<int> f(m);
for(auto &i:p) cin>>i.F>>i.S;
for(auto &i:f) cin>>i;
sort(all(p),[](pii &a,pii &b){
if(a.S!=b.S) return a.S>b.S;
return a.F>b.F;
});
sort(all(f));
reverse(all(f));
int nowf=0;
int ans=0;
for(auto &i:p){
if(i.F>f[nowf]) continue;
nowf++;
ans++;
}
cout<<ans<<"\n";
return 0;
}
