#include <bits/stdc++.h> #define fst first #define snd second #define pb push_back #define forn(i,a,b) for(int i = a; i<b; i++) #define SZ(x) (int)x.size() #define ALL(x) x.begin(),x.end() #define mset(a,v) memset(a,v,sizeof(a)) using namespace std; typedef long long ll; int main(){ ll n,m; cin>>n>>m; vector<ll> s(n); vector<ll> v(n); vector<ll> c(m); vector<pair<ll,ll>> pi(n); forn(i,0,n) cin>>s[i]>>v[i], pi[i]={v[i],s[i]}; forn(i,0,m) cin>>c[i]; sort(ALL(c)); sort(ALL(pi)); ll l = 1; ll r = SZ(c); while(l<=r){ ll mid = (l+r)/2; ll cnt = 0; ll j=SZ(c)-mid; ll i=0; while(j<SZ(c) && i<SZ(pi)){ if(pi[i].snd<=c[j]){ cnt++; i++; j++; }else{ i++; } } if(cnt<mid){ r=mid-1; }else l=mid+1; } cout<<r<<'\n'; return 0; }