#include<bits/stdc++.h>
//#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
#define pii pair<int, int>
#define fi first
#define se second
#define pb push_back
#define int long long
//#define ld long double
using namespace std;
using ll=long long;
const int inf = 1e18;
const int MN =1e5+5;
const int mod=1e9+7;
int n,m;
pii a[MN];
int b[MN];
void solve() {
cin>>n>>m;
for (int i=1; i<=n; i++) {
cin>>a[i].se>>a[i].fi;
}
sort(a+1,a+n+1);
for (int i=1; i<=m; i++) {
cin>>b[i];
}
sort(b+1,b+m+1);
int cnt=0;
int j=n;
for (int i=m; i>=1; i--) {
if(a[j].se<=b[i]) cnt++,j--;
else {
while(j>=1&&a[j].se>b[i]) j--;
if(j>0) cnt++,j--;
}
if(j==0) break;
}
cout<<cnt;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
// freopen(".inp", "r", stdin);
// freopen(".out", "w", stdout);
int t=1;
// cin>>t;
while(t--) {
solve();
}
}
