#include "bits/stdc++.h"
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
using i32 = int;
using u32 = unsigned;
using i16 = short;
using u16 = unsigned short;
using ld = long double;
using ii = pair<int, int>;
void solve() {
int n, m;
cin >> n >> m;
vector<ii> a(n);
vector<int> c(m), p(m, 0);
for(auto& [y, x] : a) cin >> x >> y;
for(int& x : c) cin >> x;
sort(a.begin(), a.end());
sort(c.begin(), c.end());
for(int i = n - 1; i >= 0; --i) {
int k = lower_bound(p.begin(), p.end(), a[i].first) - p.begin() - 1;
if(k < 0 || c[k] < a[i].second) continue;
p[k] = a[i].first;
}
int cur = m;
while(cur > 0 && p[cur - 1] > 0) --cur;
cout << m - cur << '\n';
}
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(0);
int t = 1;
//cin >> t;
while(t--) solve();
return 0;
}
