import java.util.*;
public class joi2019_ho_t2 {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int N = in.nextInt();
int M = in.nextInt();
int[][] pics = new int[N][2];
for (int i=0; i<N; i++) {
pics[i][0]=in.nextInt();
pics[i][1]=in.nextInt();
}
int[] frames = new int[M];
for (int i=0; i<M; i++) {
frames[i]=in.nextInt();
}
in.close();
Arrays.sort(pics, new Comparator<int[]>() {
@Override
public int compare(int[] a, int[] b) {
if (a[0] != b[0]) {
return Integer.compare(a[1], b[1]); // sort by first column
} else {
return Integer.compare(a[0], b[0]); // tie-break by second column
}
}
});
Arrays.sort(frames);
int fpoint=M-1; int ppoint=N-1;
while (fpoint>=0 && ppoint>=0) {
if (pics[ppoint][0] <= frames[fpoint]) {
ppoint--;
} else {
ppoint--;
fpoint++;
}
if (ppoint<0) break;
if (fpoint<0) break;
fpoint--;
}
if (fpoint<0) {
System.out.println(M);
} else {
System.out.println(M-fpoint);
}
}
}
