#include <bits/stdc++.h>
#define pb push_back
#define ll long long
#define s second
#define f first
#define left (node<<1),l,((l+r)>>1)
#define right ((node<<1)|1),((l+r)>>1) + 1,r
#define pii pair <int,int>
using namespace std;
const int N = 1e5 + 5;
pii d[N];
int a[N];
bool cmp(pii x,pii y){
return ((x.s > y.s) || (x.s == y.s && x.f > y.f));
}
signed main() {
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n,m;
cin>>n>>m;
for (int i = 1; i <= n; i++)
cin>>d[i].f>>d[i].s;
for (int i = 1; i <= m; i++)
cin>>a[i];
sort(d+1,d+n+1,cmp);
sort(a+1,a+m+1);
int r = m,ans=0;
for (int i = 1; i <= n; i++){
if (r > 0 && a[r] >= d[i].f){
++ans;
--r;
}
}
cout<<ans;
}
