#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC optimize("-Ofast")
#include <bits/stdc++.h>
#include <algorithm>
#include <iostream>
#include <vector>
#include <limits>
#include <cmath>
#include <stack>
#include <queue>
#include <map>
#include <math.h>
using namespace std;
using ll = long long;
#define v first
#define s second
bool check(ll mid, vector<pair<ll, ll>> &a, ll n, ll m, vector<ll> &c){
//cout << mid << endl;
ll idx = 0;
for(ll i = mid; i < m; i++){
if(idx >= n){
return false;
}
while(a[idx].s > c[i]){
idx++;
if(idx == n){
return false;
}
}
idx++;
}
return true;
}
void solve(){
ll n, m;
cin >> n >> m;
vector<pair<ll, ll>> a(n, pair<ll, ll>{0, 0});
vector<ll> c(m, 0);
for(ll i = 0; i < n; i++){
cin >> a[i].s >> a[i].v;
}
for(ll i = 0; i < m; i++){
cin >> c[i];
}
sort(a.begin(), a.end());
sort(c.begin(), c.end());
ll l = -1;
ll r = m;
while(l + 1 < r){
ll mid = (l + r)/2;
if(check(mid, a, n, m, c)){
r = mid;
}else{
l = mid;
}
}
cout << m - r;
}
int main(){
ios_base::sync_with_stdio(false);
cout.tie(0);
cin.tie(0);
ll t = 1;
while(t--){
solve();
}
}
