// #pragma optimize ("g",on)
// #pragma GCC optimize ("inline")
// #pragma GCC optimize ("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC optimize ("03")
#include <bits/stdc++.h>
#define pb push_back
#define SS ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr);
#define int long long
#define all(v) v.begin(),v.end()
using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
const int N = 4e5 + 1, inf = 1e9 + 1, mod = 998244353;
pair<int, int> t[4 * N];
int add[4 * N];
pair<int, int> f(pair<int, int> a, pair<int, int> b){
if(a.first > b.first) return a;
else if(a.first < b.first) return b;
else if(a.second < b.second) return a;
else return b;
}
void push(int v, int tl, int tr){
t[v].first = max(t[v].first, add[v]);
if(tl < tr){
add[v * 2] = max(add[v * 2], add[v]);
add[v * 2 + 1] = max(add[v * 2 + 1], add[v]);
}
add[v] = 0;
}
void build(int v, int tl, int tr){
if(tl == tr){
t[v] = {0, tl};
return;
}
int mid = (tl + tr) / 2;
build(v * 2, tl, mid);
build(v * 2 + 1, mid + 1, tr);
t[v] = f(t[v * 2], t[v * 2 + 1]);
}
void upd(int v, int tl, int tr, int l, int r, int x){
push(v, tl, tr);
if(tl > r || l > tr) return;
if(tl >= l && r >= tr){
add[v] = max(add[v], x);
push(v, tl, tr);
return;
}
int mid = (tl + tr) / 2;
upd(v * 2, tl, mid, l, r, x);
upd(v * 2 + 1, mid + 1, tr, l, r, x);
t[v] = f(t[v * 2], t[v * 2 + 1]);
}
pair<int, int> get(int v, int tl, int tr, int l, int r){
push(v, tl, tr);
if(tl > r || l > tr) return {-inf, inf};
if(tl >= l && r >= tr) return t[v];
int mid = (tl + tr) / 2;
return f(get(v * 2, tl, mid, l, r), get(v * 2 + 1, mid + 1, tr, l, r));
}
void solve(){
int n, m;
cin >> n >> m;
pair<int, int> p[n + 1];
int s[m + 1];
vector<int> v;
for(int i = 1; i <= n; i++){
cin >> p[i].first >> p[i].second;
}
for(int i = 1; i <= m; i++){
cin >> s[i];
}
build(1, 1, m);
sort(s + 1, s + m + 1);
sort(p + 1, p + n + 1, [&](pair<int, int> a, pair<int, int> b){
if(a.second != b.second) return a.second < b.second;
return a.first > b.first;
});
int ans = 0;
int j = m;
for(int i = n; i >= 1; i--){
if(j >= 1 && p[i].first <= s[j]){
ans++;
j--;
}
}
cout << ans;
}
signed main(){
SS
// freopen("trains.in", "r", stdin);
// freopen("trains.out", "w", stdout);
int t = 1;
// cin >> t;
while(t--){
solve();
}
}
