#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#define ll long long
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define all(v) (v).begin(),(v).end()
using namespace std;
const int N = 100005;
pair <int, int> a[N];
int b[N];
int main() {
ios_base :: sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, m;
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> a[i].S >> a[i].F;
}
for (int i = 1; i <= m; i++) {
cin >> b[i];
}
sort(a + 1, a + n + 1);
sort(b + 1, b + m + 1);
int res = 0;
for (int i = n, j = m; i >= 1 && j >= 1; i--) {
if (a[i].S <= b[j]) {
res++, j--;
}
}
cout << res << endl;
return 0;
}
