#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
ll i, j, k, n, m, c[100007]; pair<ll, ll> p[100007];
bool cmp(pair<ll, ll> x, pair<ll, ll> y){
if(x.second == y.second) return x.first < y.first;
else return x.second < y.second;
}
void run(){
cin >> n >> m;
for( i = 1; i <= n; i++) cin >> p[i].first >> p[i].second;
for( i = 1; i <= m; i++) cin >> c[i];
sort(c+1, c+m+1);
sort(p+1, p+n+1, cmp);
i = n; j = m;
while(j >= 1){
while(i >= 1 && c[j] < p[i].first) i--;
if(i < 1) break;
i--; j--;
} cout << m-j << '\n';
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
// int tt; cin >> tt; while(tt--)
run();
}
