#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define eb emplace_back
#define mt make_tuple
#define all(x) (x).begin(), (x).end()
#define sz(x) int(x.size())
#define MOD 1000000007
typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;
const ll INF=LLONG_MAX;
const int mxn=1e5+5;
bool DEBUG=0;
ii pic[mxn];
int dis[mxn];
int n,m;
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
//freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
cin >> n >> m;
for(int i=0; i<n; i++){
cin >> pic[i].se >> pic[i].fi;
}
for(int i=0; i<m; i++){
cin >> dis[i];
}
sort(pic,pic+n);
sort(dis,dis+m);
int nn=n-1,mm=m-1;
int ans = 0;
while(nn>=0&&mm>=0){
if(pic[nn].se<=dis[mm]){
ans++;
nn--;
mm--;
}else nn--;
}
cout << ans << '\n';
}
// READ & UNDERSTAND
// ll, int overflow, array bounds, memset(0)
// special cases (n=1?), n+1 (1-index)
// do smth instead of nothing & stay organized
// WRITE STUFF DOWN
