#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e5;
int n, m, S[N + 5], V[N + 5], C[N + 5], arr[N + 5], dp[N + 5];
pair<int, int> tree[N + 5];
pair<int, int> combine(pair<int, int>a, pair<int, int>b) {
if (a.first > b.first) return a;
else if (a.first < b.first) return b;
else return {a.first, min(a.second, b.second)};
}
void update(int n, int k, pair<int, int>v) {
for (; k <= n; k += k&-k) tree[k] = combine(tree[k], v);
}
pair<int, int> query(int k) {
pair<int, int> ans = {0, 0};
for (; k; k -= k&-k) ans = combine(ans, tree[k]);
return ans;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
for (int i = 1; i <= n; i++) cin >> S[i] >> V[i];
for (int i = 1; i <= m; i++) cin >> C[i];
for (int i = 1; i <= n; i++) arr[i] = i;
sort(arr + 1, arr + n + 1, [&](int a, int b) {
if (V[a] == V[b]) return S[a] < S[b];
else return V[a] < V[b];
});
sort(C + 1, C + m + 1);
C[m + 1] = 1e18;
vector<int> par(n + 5);
for (int i = 1; i <= n; i++) {
if (S[arr[i]] > C[m]) continue;
int l = lower_bound(C + 1, C + m + 2, S[arr[i]]) - (C + 1) + 1;
pair<int, int> ans = query(m - 1);
dp[i] = ans.first + 1;
par[i] = ans.second + 1;
int nexPos = max(l, ans.second + 1);
update(m, nexPos, {dp[i], nexPos});
}
cout << *max_element(dp + 1, dp + n + 1) << '\n';
//for (int i = 1; i <= n; i++) cout << S[arr[i]] << " " << C[par[i]] << " " << dp[i] << '\n';
return 0;
}
