#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
// Surat strukturasi
struct Picture {
int s, v;
};
// Suratlarni qiymati (V) bo'yicha tartiblash uchun funksiya
bool comparePictures(const Picture& a, const Picture& b) {
return a.v < b.v;
}
int main() {
// Tezkor kiritish-chiqarish
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int N, M;
cin >> N >> M;
vector<Picture> pics(N);
for (int i = 0; i < N; i++) {
cin >> pics[i].s >> pics[i].v;
}
vector<int> frames(M);
for (int i = 0; i < M; i++) {
cin >> frames[i];
}
// Suratlarni qiymati bo'yicha, ramkalarni o'lchami bo'yicha tartiblaymiz
sort(pics.begin(), pics.end(), comparePictures);
sort(frames.begin(), frames.end());
int ans = 0;
int frame_ptr = M - 1; // Eng katta ramkadan boshlaymiz
// Suratlarni eng qimmatlisidan boshlab tekshiramiz
for (int i = N - 1; i >= 0; i--) {
// Agar surat joriy ramkaga sig'sa
if (frame_ptr >= 0 && pics[i].s <= frames[frame_ptr]) {
ans++;
frame_ptr--; // Bu ramka band bo'ldi, keyingisiga o'tamiz
}
}
cout << ans << endl;
return 0;
}
