#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
// #define cerr if(false) cerr
#define watch(x) cerr << (#x) << " is " << (x) << endl;
#define endl '\n'
#define ld long double
#define int long long
#define pii pair<int, int>
#define fi first
#define se second
#define sz(a) (int)(a).size()
#define all(x) (x).begin(), (x).end()
const int maxn = 100500;
int n, m;
pii a[maxn];
signed main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
// .fi = value, .se = size
for(int i = 1; i <= n; i++) {
cin >> a[i].se >> a[i].fi;
}
priority_queue<int> pq;
for(int i = 1; i <= m; i++) {
int x;
cin >> x;
pq.push(-x);
}
sort(a+1, a+n+1);
// size of last frame
int lst = -1e18;
int ans = 0;
for(int i = 1; i <= n; i++) {
if(a[i].se >= lst) {
while(sz(pq) and -pq.top() < a[i].se) pq.pop();
if(sz(pq)) {
lst = a[i].se;
pq.pop();
ans++;
}
}
}
cout << ans << endl;
}
/*
sort by value then by size
Did you read the bounds?
Did you make typos?
Are there edge cases (N=1?)
Are array sizes proper?
Integer overflow?
DS reset properly between test cases?
Is using long longs causing TLE?
Are you using floating points?
*/
