#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
using namespace std;
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int n, m, ans = 0;
cin>>n>>m;
vector<pair<int,int>> vec(n);
vector<int> c(m);
for (int i=0;i<n;i++)
cin>>vec[i].second>>vec[i].first;
sort(begin(vec), end(vec));
for (int i=0;i<m;i++)
cin>>c[i];
sort(begin(c), end(c));
int l = -1, r = m;
while (l + 1 < r){
int mid = (l + r) / 2, ptr = mid;
for (int i=0;i<n;i++){
if (ptr < m and vec[i].second <= c[ptr])
ptr++;
}
if (ptr == m)
r = mid;
else
l = mid;
}
cout<<m - r<<endl;
}
