/*
//\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\\
\\ //
// 271828___182845__904523__53602__ \\
\\ 87___47____13______52____66__24_ //
// 97___75____72______47____09___36 \\
\\ 999595_____74______96____69___67 //
// 62___77____24______07____66__30_ \\
\\ 35___35____47______59____45713__ //
// \\
\\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\//
*/
#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <cmath>
#include <climits>
#include <algorithm>
#include <random>
#include <queue>
#include <deque>
#include <iomanip>
#include <string>
#include <tuple>
#include <bitset>
#include <chrono>
#include <ctime>
#include <fstream>
#include <stack>
#include <cstdio>
using namespace std;
using ll = long long;
const int N = 3e5 + 5;
const ll mod = 1e9 + 7, inf = 1e18;
void solve() {
int n, m; cin >> n >> m;
vector<pair<int, int>> vp(n);
vector<int> c(m);
for (int i = 0; i < n; ++i) {
cin >> vp[i].second >> vp[i].first;
}
for (int i = 0; i < m; ++i) cin >> c[i];
sort(vp.rbegin(), vp.rend());
sort(c.rbegin(), c.rend());
// vp[i].second
int ans = 0;
for (int i = 0, j = 0; i < n && j < m; ++i) {
if (vp[i].second <= c[j]) {
++j;
++ans;
}
}
cout << ans << "\n";
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
//int t; cin >> t;
//while (t--)
solve();
}
