#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define FOR(i, a, b) for(int i = (int)a; i <= (int)b; i++)
#define DEC(i, a, b) for(int i = (int)a; i >= (int)b; i--)
typedef pair<int, int> pi;
#define f first
#define s second
#define pb push_back
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
int n, m, f[100005], ans;
pi p[100005]; //value, size
int main() {
fastio; cin >> n >> m;
FOR(i, 1, n) cin >> p[i].s >> p[i].f;
FOR(i, 1, m) cin >> f[i];
sort(p+1, p+n+1);
sort(f+1, f+m+1);
DEC(i, n, 1) {
if (f[m-ans] >= p[i].s) {
ans++;
if (ans == m) break;
}
}
cout << ans;
}
