// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
template<class T> using V = vector<T>;
int main() {
cin.tie(0)->sync_with_stdio(0);
int N, M; cin >> N >> M;
V<array<int, 2>> A(N); for(auto& x : A) cin >> x[1] >> x[0];
V<int> MX(M); for(auto& x : MX) { cin >> x; }
sort(rbegin(A), rend(A));
sort(rbegin(MX), rend(MX));
int ans = 0;
for(int i = 0; i < N; i++) {
int x = A[i][1]; /*cout << MX[ans] << " " << x << endl;*/
if (MX[ans] >= x) ans++;
if (ans == M) break;
}
cout << ans << nl;
return 0;
}
