#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define in insert
#define lb lower_bound
#define F first
#define int long long
#define S second
#define sz size()
#define all(v) v.begin(),v.end()
#define FOR(x, n, m, d) for(int x = n; x <= m; x += d)
#define FORR(x, n, m, d) for(int x = n; x >= m; x -= d)
#define nikita ios_base::sync_with_stdio(0), cin.tie(0);
const int N = 2e5+5;
int a[N], ans, inf = 1e18, par = 0, c[N], t[N*6], d[N], dp[N];
int n,m,k,sum=0,x,y, r, l, mod = 1e9+7;
void upd(int pos, int val, int v = 1, int tl = 1, int tr = n){
    if(tl == tr){
        t[v] = val;
        return;
    }
    int tm = (tl + tr) >> 1;
    if(pos <= tm)upd(pos, val, v*2, tl, tm);
    else upd(pos, val, v*2+1, tm+1, tr);
}
int get(int r, int v = 1, int tl = 1, int tr = n){
    if(tr <= r)return t[v];
    if(tl > r)return 0;
    int tm = (tl + tr) >> 1;
    return max(get(r, v*2, tl, tm), get(r, v*2+1, tm+1, tr));
}
void build(int v = 1, int tl = 1, int tr = n){
    if(tl==tr){d[tl] = v;return;}
    int tm = (tl + tr) >> 1;
    build(v*2, tl,  tm), build(v*2+1, tm+1, tr);
}
void solve() {
	nikita
	vector<pair<int, int>>v;
	cin >> n >> m;
	FOR(i, 0, n-1, 1){
	    cin >> x >> y;
	    v.pb({y, x});
	}
	build();
	FOR(i, 1, m, 1)cin >> a[i];
	sort(a+1, a+m+1);
	sort(all(v));
	for(auto i : v){
	    FOR(j, 1, m, 1){
	        if(a[j] >= i.S)
	        dp[j] = get(j-1) + 1;
	        else dp[j] = t[d[j]];
	        ans = max(ans, dp[j]);
	    }
	    FOR(j, 1, m, 1){
	        upd(j, dp[j]);
	    }
	}
	cout << ans;
}
signed main() {
	nikita
//	freopen("cardgame.in", "r", stdin);
//    freopen("cardgame.out", "w", stdout);
	int tt = 1;
	if(!tt)cin >> tt;
	FOR(i, 1, tt, 1)solve();
}/*
cin >> n >> m;
	FOR(i,1 , n, 1)cin >> a[i];
	sort(a+1, a+n+1);
	l = a[1], r = a[n];
	while(l <= r){
	    int md = (l + r) >> 1;
	    sum = cnt = 0;
	    FOR(i, 1, n, 1){
	        sum += max(md - a[i], (int)0);
	        cnt += max((int)0, a[i] - md - m);
	    }
	    if(cnt >= sum)l = md + 1;, ans = md;
	    else r = md - 1;
	}
	
*/
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