#include <bits/stdc++.h>
using namespace std;
#define VA_NUM_ARGS(...) VA_NUM_ARGS_IMPL_((0,__VA_ARGS__, 6,5,4,3,2,1))
#define VA_NUM_ARGS_IMPL_(tuple) VA_NUM_ARGS_IMPL tuple
#define VA_NUM_ARGS_IMPL(_0,_1,_2,_3,_4,_5,_6,N,...) N
#define macro_dispatcher(macro, ...) macro_dispatcher_(macro, VA_NUM_ARGS(__VA_ARGS__))
#define macro_dispatcher_(macro, nargs) macro_dispatcher__(macro, nargs)
#define macro_dispatcher__(macro, nargs) macro_dispatcher___(macro, nargs)
#define macro_dispatcher___(macro, nargs) macro ## nargs
#define Debug1(a) cout<<#a<<"="<<(a)<<"\n"
#define Debug2(a,b) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<"\n"
#define Debug3(a,b,c) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<"\n"
#define Debug4(a,b,c,d) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<"\n"
#define Debug5(a,b,c,d,e) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<"\n"
#define Debug6(a,b,c,d,e,f) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<", "<<#f<<"="<<(f)<<"\n"
#define Debug(...) macro_dispatcher(Debug, __VA_ARGS__)(__VA_ARGS__)
#define DA(a,s,n) cout<<#a<<"=["; printarray(a,s,n); cout<<"]\n"
#define TT1 template<class T>
#define TT1T2 template<class T1, class T2>
#define TT1T2T3 template<class T1, class T2, class T3>
template<class T, size_t N> ostream& operator << (ostream& os, const array<T, N>& v);
TT1T2 ostream& operator << (ostream& os, const pair<T1, T2>& p){ return os <<"("<<p.first<<", "<< p.second<<")"; }
TT1 ostream& operator << (ostream& os, const vector<T>& v){ bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
template<class T, size_t N> ostream& operator << (ostream& os, const array<T, N>& v) { bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const set<T1, T2>&v){ bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const multiset<T1,T2>&v){bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2T3 ostream& operator << (ostream& os, const map<T1,T2,T3>& v){ bool f = 1; os << "["; for (auto& ii : v) { if (!f)os << ", "; os << "(" << ii.first << " -> " << ii.second << ") "; f = 0; }return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const multimap<T1, T2>& v){ bool f = 1; os << "["; for (auto& ii : v) { if (!f)os << ", "; os << "(" << ii.first << " -> " << ii.second << ") "; f = 0; }return os << "]"; }
TT1T2 ostream& operator << (ostream& os, priority_queue<T1, T2> v) { bool f = 1; os << "["; while (!v.empty()) { auto x = v.top(); v.pop(); if (!f) os << ", "; f = 0; os << x; } return os << "]"; }
TT1T2 void printarray(const T1& a, T2 l, T2 r){ for (T2 i = l; i<=r; i++) cout << a[i] << (i<r?" ":""); }
void cio(){
ios::sync_with_stdio(false);
cin.tie(NULL);
//cout << setprecision(15);
}
#define tt() printf("%.4f sec\n", (double) clock() / CLOCKS_PER_SEC )
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define Fi first
#define Se second
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define rep(i, n) for(int i=0;i<n;i++)
#define repp(i, n) for(int i=1;i<=n;i++)
#define all(x) x.begin(), x.end()
#define geti1(X) cin >> X
#define geti2(X,Y) cin >> X >> Y
#define geti3(X,Y,Z) cin >> X >> Y >> Z
#define geti4(X,Y,Z,W) cin >> X >> Y >> Z >> W
#define GET_MACRO(_1,_2,_3,_4,NAME,...) NAME
#define geti(...) GET_MACRO(__VA_ARGS__, geti4, geti3, geti2, geti1) (__VA_ARGS__)
#define endl '\n'
typedef tuple<int,int,int> t3;
typedef tuple<int,int,int,int> t4;
void die(){printf("-1\n"); exit(0);}
int xx[8] = {1,-1,0,0,1,1,-1,-1}, yy[8] = {0,0,1,-1,1,-1,1,-1};
const ll mod = 1e9+7;
int N,M;
struct Node{
int x,y,t;
};
vector<Node> v;
int dp[500500];
int mx[500500];
int main(){
scanf("%d%d",&N,&M);
repp(i,N){
int x,y; scanf("%d%d",&x,&y);
v.push_back({x,y,0});
}
repp(i,M) {
int x; scanf("%d",&x);
v.push_back({x,2000000000,1});
}
int timer = 0;
sort(all(v), [](Node a, Node b)->bool{
if( a.x != b.x ) return a.x < b.x;
if( a.y != b.y ) return a.y < b.y;
return a.t < b.t;
});
for(auto& e : v) e.x = ++timer;
sort(all(v), [](Node a, Node b)->bool{
if( a.y != b.y ) return a.y < b.y;
if( a.x != b.x ) return a.x < b.x;
return a.t < b.t;
});
timer = 0;
for(auto& e : v) if( e.y <= 1e9+100) e.y = ++timer;
sort(all(v), [](Node a, Node b)->bool{
if( a.x != b.x ) return a.x < b.x;
if( a.y != b.y ) return a.y < b.y;
return a.t < b.t;
});
vector<int> tlist;
for(auto e : v){
int x = e.x ,y = e.y ,t = e.t;
//Debug(x,y,t);
if( t == 0 ){
tlist.push_back(y);
}
else{
for(int i=1;i<=2010;i++) mx[i] = max(mx[i-1], dp[i]);
for(auto p : tlist){
dp[p] = max(dp[p], mx[p-1]+1);
// Debug( p, dp[p]);
}
}
}
int ans = 0;
repp(i, 2010) ans = max(ans, dp[i]);
printf("%d\n",ans);
}
