#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define x first
#define y second
vector<pair<ll, ll>> P;
vector<ll> C;
int dp[100002];
void solve(){
int N, M;
cin>>N>>M;
P.assign(N, pair<ll, ll>());
C.assign(M, 0);
for(int i = 0; i < N; i++)
cin>>P[i].x>>P[i].y;
for(int j = 0; j < M; j++)
cin>>C[j];
sort(C.begin(), C.end());
sort(P.begin(), P.end(), [&](pair<ll, ll> p1, pair<ll, ll> p2){
return p1.second < p2.second || (p1.second == p2.second && p1.first < p2.first);
});
int ans = 0;
int j = M-1;
for(int i = N-1; i >= 0; i--){
if(j >= 0 && P[i].first <= C[j]){
j--;
ans++;
}
}
cout<<ans<<endl;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
solve();
return 0;
}
