#include <bits/stdc++.h>
using namespace std;
const long long INFll = (long long) 1e18 + 10;
const int INFii = (int) 1e9 + 10;
typedef long long ll;
typedef int ii;
typedef long double dbl;
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
#define maxn 100010
ii n, m, c[maxn];
pair<ii,ii> p[maxn];
int main() {
ios::sync_with_stdio(false); cin.tie(0);
//freopen("in.in", "r", stdin);
//freopen("out.out", "w", stdout);
cin >> n >> m;
for(ii i = 1; i <= n; i++) {
cin >> p[i].sc >> p[i].fr;
}
for(ii i = 1; i <= m; i++) {
cin >> c[i];
}
sort(p+1,p+1+n);
sort(c+1,c+1+m);
ii p1 = n;
ii p2 = m;
ii ans = 0;
while(p1 > 0 && p2 > 0) {
if(p[p1].sc <= c[p2]) {
ans++;
p1--;
p2--;
}
else {
p1--;
}
}
cout << ans << endl;
}
