#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const int LIM=1e5+7;
pair<int,int>T[LIM];
int P[LIM];
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int n, m;
cin >> n >> m;
rep(i, n) cin >> T[i].nd >> T[i].st;
rep(i, m) cin >> P[i];
sort(T, T+n);
sort(P, P+m);
reverse(T, T+n);
reverse(P, P+m);
int ans=0;
rep(i, n) if(ans<m && T[i].nd<=P[ans]) ++ans;
cout << ans << '\n';
}
