#include <bits/stdc++.h>
// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define int long long
#define ld long double
#define ll long long
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
using namespace std;
const int oo = 1e18 + 9;
const int MAX = 5000 + 5, LOGMAX = 20, B = 441, MOD = 998244353;
void solve(){
int n, m; cin >> n >> m;
vector<pii> v(n);
for(auto &[b, a] : v){
cin >> a >> b;
}
vector<int> c(m);
for(int &a : c) cin >> a;
sort(all(c));
reverse(all(c));
sort(all(v));
int l = 1, r = min(n, m);
while(l < r){
int mid = (l + r + 1) / 2;
int j = mid - 1;
for(auto [b, a] : v){
if(a <= c[j]) j--;
if(j == -1) break;
}
if(j == -1) l = mid;
else r = mid - 1;
}
cout << l << '\n';
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
while(t--) solve();
}
