#include <bits/stdc++.h>
#define fast ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL)
#define ll long long int
#define ld long double
using namespace std;
const int N = 1e6 + 5;
const int MOD = 1e9 + 7;
bool vis[N];
void solve(){
long long int n, m;
cin >> n >> m;
pair<long long int, long long int> a[n];
long long int b[m];
for(int i = 0; i < n; ++i)
cin >> a[i].second>> a[i].first;
sort(a, a + n);
for(int i = 0; i < m; ++i)
cin >> b[i];
sort(b, b + m);
long long int ans1 = 0;
for(int k = 0; k < n; ++k){
for(int j = 0; j < m; ++j)
vis[j] = 0;
long long int ans = 0, pre = 0;
for(int i = k; i < n; ++i){
long long int x = a[i].second;
for(int j = 0; j < m; ++j){
if(b[j] >= x and vis[j] == 0 and b[j] >= pre){
vis[j] = 1;
++ans;
pre = b[j];
break;
}
}
}
// cout << ans << '\n';
ans1 = max(ans1, ans);
}
cout << ans1;
}
int main(){
fast;
int t = 1;
// cin >> t;
while(t--)
solve();
return 0;
}
