#undef _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define int long long
#define pb push_back
#define fi first
#define si second
#define ar array
typedef pair<int,int> pi;
typedef tuple<int,int,int> ti;
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {cerr << " " << to_string(H);debug_out(T...);}
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
int N, M, ans;
int frame[100010];
pi pic[100010];
signed main() {
fast;
cin >> N >> M;
for (int i = 1; i <= N; ++i) cin >> pic[i].fi >> pic[i].si;
for (int i = 1; i <= M; ++i) cin >> frame[i];
sort(frame + 1, frame + 1 + M, greater<int>());
sort(pic + 1, pic + 1 + N, [](pi a, pi b) {
if (a.si == b.si) return a.fi > b.fi;
return a.si > b.si;
});
int idx = 1;
for (int i = 1; i <= M; ++i) {
while (idx <= N && pic[idx].fi > frame[i]) ++idx;
if (idx == N + 1) break;
++ans; ++idx;
}
cout << ans;
return 0;
}
