//Never stop trying
#include "bits/stdc++.h"
using namespace std;
#define boost ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
typedef long long ll;
typedef string str;
typedef long double ld;
typedef pair<int, int> pi;
#define fi first
#define se second
typedef vector<int> vi;
typedef vector<pi> vpi;
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define endl "\n"
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
const int MOD = 1e9 + 7; //998244353
const ll INF = 1e18;
const int MX = 2e5 + 10;
const int nx[4] = {0, 0, 1, -1}, ny[4] = {1, -1, 0, 0}; //right left down up
template<class T> bool ckmin(T& a, const T& b) { return a > b ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
ll cdiv(ll a, ll b) { return a / b + ((a ^ b) > 0 && a % b); } // divide a by b rounded up
//constexpr int log2(int x) { return 31 - __builtin_clz(x); } // floor(log2(x))
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
//mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
ll random(ll a, ll b){
return a + rng() % (b - a + 1);
}
#ifndef LOCAL
#define cerr if(false) cerr
#endif
#define dbg(x) cerr << #x << " : " << x << endl;
#define dbgs(x,y) cerr << #x << " : " << x << " / " << #y << " : " << y << endl;
#define dbgv(v) cerr << #v << " : " << "[ "; for(auto it : v) cerr << it << ' '; cerr << ']' << endl;
#define here() cerr << "here" << endl;
void IO() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
}
/////////////////////////ONLY CLEAN CODES ALLOWED/////////////////////////
int N,M;
vi S,V,C;
vpi vec;
bool cmp(int i, int j){
if(V[i]!=V[j]) return V[i] > V[j];
return S[i] > S[j];
}
bool cmp2(int i, int j){
return S[i] < S[j];
}
int main() {
boost; IO();
cin>>N>>M;
S.resize(N); V.resize(N); C.resize(M);
FOR(i,0,N) cin>>S[i]>>V[i];
FOR(i,0,M) cin>>C[i];
sort(all(C));
vi vec;
multiset<int,bool(*)(int,int)>s(cmp);
FOR(i,0,N){
vec.pb(i);
s.insert(i);
}
sort(all(vec),cmp2);
int ans=0;
ROF(i,0,M){
while(sz(vec) && S[vec.back()]>C[i]){
if(s.count(vec.back()))
s.erase(s.find(vec.back()));
vec.pop_back();
}
if(!sz(s)) break;
s.erase(s.begin());
ans++;
}
cout << ans << endl;
return 0;
}
//Change your approach
