// #pragma GCC diagnostic warning "-std=c++11"
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize ("O3")
// #pragma GCC optimization ("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define eb emplace_back
#define mp make_pair
#define pb push_back
#define pp pop_back
#define endl '\n'
#define ff first
#define ss second
#define stop exit(0)
#define sz(x) (int)x.size()
#define pause system("pause")
#define all(x) (x).begin(),(x).end()
#define deb(x) cout << #x << "-" << x << endl
typedef char chr;
typedef string str;
typedef long long ll;
typedef vector<int> vii;
typedef pair<int, int> pii;
const long long INF = LLONG_MAX;
const int inf = INT_MAX;
const int mod = 998244353;
const int MOD = 1e9 + 7;
const int dx[] = {0, 0, -1, 1};
const int dy[] = {-1, 1, 0, 0};
const double PI = 2 * acos(0.0);
const int N = 2e5 + 5;
int n,m,ans;
int b[N];
pii a[N];
bool check(int x) {
int pos = m-x+1;
for (int i = 1; i<= n; i++) {
if (b[pos] >= a[i].ss) {
pos++;
}
if (pos > m) break;
}
return (pos > m);
}
inline void test_case() {
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> a[i].ss >> a[i].ff;
}
sort(a+1,a+1+n);
for (int i = 1; i <= m; i++) {
cin >> b[i];
}
sort(b+1,b+1+m);
int l = 0; int r = m;
while (l <= r) {
int mid = (l+r)/2;
if (check(mid)) {
ans = mid;
l = mid + 1;
} else {
r = mid - 1;
}
}
cout << ans << endl;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int T = 1;
// cin >> T;
while (T--) {
test_case();
}
return 0;
}
