#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define sz second
#define val first
#define pii pair<int, int>
const int N = 1e5 + 5;
int n, m, c[N];
pii a[N];
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m;
for(int i = 1; i <= n; ++i) cin >> a[i].sz >> a[i].val;
for(int i = 1; i <= m; ++i) cin >> c[i];
sort(a + 1, a + n + 1, greater<>());
sort(c + 1, c + m + 1, greater<>());
int cnt = 0;
for(int i = 1; i <= n; ++i) {
if(a[i].sz <= c[cnt + 1]) {
++cnt;
}
}
cout << cnt;
return 0;
}
