import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.*;
public class joi2019_ho_t2 {
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer(br.readLine());
int n = Integer.parseInt(st.nextToken());
int m = Integer.parseInt(st.nextToken());
Picture[] pictures = new Picture[n];
for(int i = 0; i < n; i++){
st = new StringTokenizer(br.readLine());
pictures[i] = new Picture(Integer.parseInt(st.nextToken()), Integer.parseInt(st.nextToken()));
}
Arrays.sort(pictures);
int[] frames = new int[m];
for(int i = 0; i < m; i++){
frames[i] = Integer.parseInt(br.readLine());
}
Arrays.sort(frames);
int f_index = m-1;
int p_index = n-1;
for(; f_index >= 0; f_index--){
if(pictures[p_index].size <= frames[f_index]){
p_index--;
}else{
p_index--;
f_index++;
}
if(p_index == -1){
break;
}
}
if(f_index == -1){
System.out.println(m);
}else {
System.out.println(m - f_index);
}
}
static class Picture implements Comparable<Picture>{
int size;
int value;
public Picture(int a, int b){
this.size = a;
this.value = b;
}
public int compareTo (Picture p){
if(this.value != p.value) return this.value-p.value;
return this.size - p.size;
}
}
}
