#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define pb push_back
#define int long long
#define pint pair<int, int>
#define vint vector<pair<int, int>>
const int mod = 1e9 + 7;
const int shrek = 5e5 + 5;
const int say = INT_MAX;
const int gex = INT_MIN;
const int oo = 1e9;
// bool cmp(const pint&a, const pint&b) {
// if(a.ff == b.ff) {
// return a.ss < b.ss;
// }
// return a.ff > b.ff;
// }
signed main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m; cin >> n >> m;
int c[m];
vector<pair<int, int>> pic(n);
for(int i = 0; i < n; i++) {
cin >> pic[i].ss >> pic[i].ff;
}
sort(pic.begin(), pic.end());
reverse(pic.begin(), pic.end());
for(int i = 0; i < m; i++) cin >> c[i];
sort(c, c + m);
reverse(c, c + m);
int l = 0, r = 0;
int ans = 0;
while(l < n && r < m) {
if(pic[l].ss <= c[r]) {
ans++;
l++;
r++;
continue;
}
l++;
}
cout << ans << '\n';
return 0;
}
