/*
author : PakinDioxide
created : 25/04/2025 20:25
task : JOI19_ho_t2
*/
#include <bits/stdc++.h>
#define ll long long
using namespace std;
int main() {
ios::sync_with_stdio(0), cin.tie(0);
int n, m;
cin >> n >> m;
pair <ll, ll> A[n];
ll a[n], b[m];
for (auto &[x, y] : A) cin >> y >> x;
for (auto &e : b) cin >> e;
sort(b, b+m);
sort(A, A+n);
for (int i = 0; i < n; i++) a[n-i-1] = A[i].second;
int ans = 0, idx = m-1; ll mn = LLONG_MAX;
for (auto &e : a) {
mn = min(mn, e);
if (mn <= b[idx]) idx--, mn = LLONG_MAX, ans++;
if (idx < 0) break;
}
cout << ans << '\n';
}
