//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T>
using Tree =
tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define int long long
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define rep(i, a, b) for (int i = a; i <= b; ++i)
#define per(i, b, a) for (int i = b; i >= a; --i)
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(), (v).end()
#define lsb(x) (x)&(-x)
#define bug(x) cerr << #x << " " << x << endl;
void setIO(string name = "") {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
if (!name.empty()) {
freopen((name + ".in").c_str(), "r", stdin);
freopen((name + ".out").c_str(), "w", stdout);
}
}
ll fexp(ll a, ll b, ll m) {
if (b == 0) return 1LL;
ll p = a;
ll ans = 1;
while (b > 0) {
if (b % 2 != 0) ans = (ans * p) % m;
p = (p * p) % m;
b >>= 1;
}
return ans;
}
const int MAXN = 3e3 + 10;
const int INF = 1e18 + 5;
const int MOD = 1e9 + 7;
pii a[MAXN], v[MAXN], dp[MAXN];
int b[MAXN];
void solve() {
int n,m;cin >> n >> m;
rep(i,1,n) cin >> a[i].se >> a[i].fi;
rep(i,1,m) cin >> b[i];
sort(a+1,a+n+1);
sort(b+1,b+m+1);
dp[0] = {-INF, 0};
rep(i,1,n) dp[i] = {INF, INF};
rep(i,1,n) {
int lo = 1, hi = m, ans=m+1;
while (lo <= hi) {
int mid = (lo + hi)/2;
//cout << mid << ' ' << b[mid] << ' ' << a[i].se << '\n';
if (b[mid] >= a[i].se) {
hi = mid-1;
ans = mid;
}
else {
lo = mid + 1;
}
}
v[i] = {a[i].se,ans};
//cout << v[i].fi << ' ' << v[i].se << '\n';
}
rep(i,1,n) {
int p = upper_bound(dp,dp+n+1, v[i]) - dp;
dp[p] = {v[i].fi,max(v[i].se, dp[p-1].se+1)};
}
int ans = 0;
rep(i,1,n) {
if (dp[i].fi == INF || dp[i].se > m) break;
ans++;
}
cout << ans << '\n';
}
int32_t main() {
setIO();
int tt = 1;
//cin >> tt;
while (tt-- > 0) solve();
return 0;
}
