#include<bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define int long long
using namespace std;
const int md = 1e9 + 7;
const int maxn = 5e5;
signed main(){
int n, m;
cin >> n >> m;
vector<array<int, 2>> T;
for(int i = 0; i < n; i++){
int u, v;
cin >> u >> v;
T.push_back({v, u});
}
sort(T.rbegin(), T.rend());
vector<int> Q;
for(int i = 0; i < m; i++){
int q;
cin >> q;
Q.push_back(q);
}
sort(Q.rbegin(), Q.rend());
int j = 0;
vector<int> g;
int cur = 0;
for(int i = 0; i < n; i++){
if(T[i][1] <= Q[j]){
j += 1;
}
}
cout << j;
}
