#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAXN = 1e5 + 10;
pair<int, int> a[4*MAXN];
void update(int l, int r, int tar, int idx, int val) {
if(l == r) {
a[idx] = {val, tar};
return;
}
int mid = (l+r) / 2;
if(tar <= mid) update(l, mid, tar, 2*idx+1, val);
else update(mid+1, r, tar, 2*idx+2, val);
a[idx] = max(a[2*idx+1], a[2*idx+2]);
}
pair<int, int> query(int l, int r, int constl, int constr, int idx) {
if(l <= constl && constr <= r) return a[idx];
int mid = (constl + constr) / 2;
if(mid < l || r < constl) return query(l, r, mid+1, constr, 2*idx+2);
else if(constr < l || r < mid+1) return query(l, r, constl, mid, 2*idx+1);
else return max(query(l, r, constl, mid, 2*idx+1), query(l, r, mid+1, constr, 2*idx+2));
}
signed main() {
int N, M; cin >> N >> M;
pair<int, int> p[N+1]; for(int i=1; i<=N; i++) cin >> p[i].first >> p[i].second;
int c[M+1]; for(int i=1; i<=M; i++) cin >> c[i];
sort(p+1, p+N+1);
sort(c+1, c+M+1);
for(int i=1; i<=N; i++) update(1, N, i, 0, p[i].second);
vector<int> v;
for(int i=M; i>=1; i--) {
int lb = 1, rb = N;
while(lb < rb) {
int mid = (lb+rb+1) / 2;
if(p[mid].first <= c[i]) lb = mid;
else rb = mid-1;
}
if(p[lb].first <= c[i]) {
pair<int, int> res = query(1, lb, 1, N, 0);
if(v.size() && res.first > v.back()) return cout << M-i << '\n', 0;
if(res.first == 0) return cout << M-i << '\n', 0;
update(1, N, res.second, 0, 0);
}
else {
return cout << M-i << '\n', 0;
}
}
cout << M << '\n';
}
