#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair <ll , ll> pll;
typedef pair <int , int> pii;
#define fi first
#define se second
//#define int ll
const int intf = 2e9 , maxn = 1e5 + 5;
const ll inf = 2e18 , mod = 1e9 + 7;
void solve(){
int n , m; cin >> n >> m;
vector <pii> a(n);
vector <int> r(m);
for (auto &x : a){
cin >> x.se >> x.fi;
}
sort(a.begin() , a.end());
for (auto &x : r){
cin >> x;
}
sort(r.begin() , r.end());
int i = n - 1 , j = m - 1 , ans = 0;
while(i >= 0 && j >= 0){
if (a[i].se <= r[j]){
j--;
ans++;
}
i--;
}
cout << ans;
}
signed main() {
//freopen("input.txt" , "r" , stdin);
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); cout.precision(20);
int t = 1; //cin >> t;
while(t-->0){
solve();
}
return 0;
}
