//Suleyman Atayew
#include <algorithm>
#include <iostream>
#include <string.h>
#include <stdio.h>
#include <vector>
#include <bitset>
#include <queue>
#include <cmath>
#include <map>
#include <set>
#define N 200010
#define ff first
#define ss second
#define pb push_back
#define ll long long
#define mod 1000000007
#define pii pair <int, int>
#define sz(a) (int)(a.size())
ll bigmod(ll a, ll b) { if(b==0)return 1; ll ret = bigmod(a, b/2); return ret * ret % mod * (b%2 ? a : 1) % mod; }
using namespace std;
pii p[N];
int n, m, sz;
map <int, int> M;
int v[N];
pii T[N*4];
priority_queue <int> Q[N*4];
void upd(int pos, pii x, int l, int r, int node)
{
if(l == r) {
if(x.ff) {
Q[node].push(x.ss);
T[node] = {pos, Q[node].top()};
} else {
Q[node].pop();
if(!Q[node].empty())
T[node] = {pos, Q[node].top()};
else
T[node] = {0, 0};
}
return;
}
if(pos <= (l+r)/2)
upd(pos, x, l, (l+r)/2, node*2);
else
upd(pos, x, (l+r)/2+1, r, node*2+1);
if(T[node*2].ss > T[node*2+1].ss)
T[node] = T[node*2];
else
T[node] = T[node*2+1];
}
pii tap(int pos, int l, int r, int node)
{
if(l > pos) return {0, 0};
if(r <= pos) return {T[node].ss, T[node].ff};
return max(tap(pos, l, (l+r)/2, node*2), tap(pos, (l+r)/2+1, r, node*2+1));
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m;
vector <int> E;
for(int i = 1; i <= n; i++) {
int a, b;
cin >> a >> b;
M[a] = 1;
p[i] = {a, b};
}
for(int i = 1; i <= m; i++)
cin >> v[i], M[v[i]] = 1;
for(auto &i: M) i.ss = ++sz;
sort(v+1, v+1+m);
for(int i = 1; i <= n; i++)
upd(M[p[i].ff], {1, p[i].ss}, 1, sz, 1);
for(int i = m; i >= 0; i--) {
int x = M[v[i]];
pii ans = tap(x, 1, sz, 1);
if(ans.ss == 0 || !i) {
cout << m-i;
return 0;
}
upd(ans.ss, {0, ans.ff}, 1, sz, 1);
}
}
