#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
using namespace std;
template <class X, class Y> bool minimize(X &a, Y b) {
if (a > b) return a = b, true;
return false;
}
template <class X, class Y> bool maximize(X &a, Y b) {
if (a < b) return a = b, true;
return false;
}
const int N = 1e5 + 7;
int b[N];
pair<int, int> a[N];
signed main() {
cin.tie(0)->sync_with_stdio(0);
int n, m; cin >> n >> m;
for (int i = 1; i <= n; i ++) {
cin >> a[i].se >> a[i].fi;
}
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 = m, j = n; i > 0 && j > 0; i --) {
while (j > 0 && a[j].se > b[i]) {
j --;
}
if (j > 0) {
j --;
res ++;
}
}
cout << res;
return 0;
}
