#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
#define pb push_back
#define pii pair<int, int>
#define pll pair<ll, ll>
#define st first
#define nd second
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define debug false
const int MAXN = 100 * 1000;
pii sv[MAXN];
int c[MAXN];
bool porownaj (pii a, pii b) {
if (b.nd == a.nd) {
return a.st > b.st;
}
return a.nd > b.nd;
}
int main () {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n, m;
cin >> n >> m;
for (int i = 0; i < n; i ++) {
cin >> sv[i].st >> sv[i].nd;
}
for (int j = 0; j < m; j ++) {
cin >> c[j];
}
sort(c, c + m);
reverse(c, c + m);
sort(sv, sv + n, porownaj);
int ind = 0;
for (int i = 0; i < n; i ++) {
if (sv[i].st <= c[ind]) {
ind ++;
}
}
cout << ind << "\n";
return 0;
}
