// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
#include <numeric>
#include <stack>
#include <chrono>
using namespace std;
void fast_io(){
// freopen("", "r", stdin);
// freopen("", "w", stdout);
ios::sync_with_stdio(0);
cin.tie(); cout.tie();
cout << setprecision(9);
}
#define int long long
#define endl '\n'
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define fi first
#define se second
void solve() {
int n, m; cin >> n >> m;
int S[n + 1], V[n + 1], C[m + 1];
vector<pair<int, int>> p;
set<int> s;
for (int i = 1; i <= n; i++) {
cin >> S[i] >> V[i];
p.push_back({V[i], S[i]});
}
for (int i = 0; i < m; i++) cin >> C[i];
sort(all(p));
for (int i = 0; i < n; i++){
auto [u, v] = p[i];
p[i] = {v, u};
}
sort(C, C + m);
reverse(C, C + m);
int ans = 0;
for (int i = n - 1, j = 0; i >= 0 && j < m; i--){
if (p[i].first <= C[j])
{
j++;
ans++;
}
}
cout << ans << endl;
return;
}
signed main() {
fast_io();
srand(chrono::steady_clock::now().time_since_epoch().count());
int tc = 1;
// cin >> tc;
while (tc--) solve();
return 0;
}
