#include<bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define pb push_back
using namespace std;
using ll = long long;
using vi = vector<ll>;
using pi = pair<ll, ll>;
const int maxn= 1e5 + 55;
int n, m;
vector<pi> a;
vi b;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
a.resize(n);
b.resize(m);
for(int i = 0; i < n; i++) cin >> a[i].second >> a[i].first;
for(int i = 0; i < m; i++) cin >> b[i];
sort(all(a));
sort(all(b));
int j = n-1, ans = 0;
for(int i = m; i--;) {
while(j>=0&&a[j].second>b[i]) j--;
if(j<0) break;
ans++;
j--;
}
cout << ans;
}
