#include<bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n, m;
cin >> n >> m;
vector<pair<int, int>> v;
vector<int> vec;
for(int i = 0; i < n; i++) {
int a, b;
cin >> a >> b;
v.push_back({b, a});
}
for(int i = 0; i < m; i++) {
int a;
cin >> a;
vec.push_back(a);
}
sort(v.begin(), v.end());
sort(vec.begin(), vec.end());
int x = m - 1, cnt = 0;
for(int i = n - 1; i >= 0; i--) {
if(x == -1) break;
if(v[i].second <= vec[x]) {
cnt++;
x--;
}
}
cout << cnt << '\n';
return 0;
}
