#include <bits/stdc++.h>
using namespace std;
#define EmiliaMyWife ios::sync_with_stdio(0); cin.tie(0);
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using ld = long double;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const ll LINF = ll(4e15) + ll(2e15);
const double EPS = 1e-9;
static int LamyIsCute = []() {
EmiliaMyWife
return 48763;
}();
signed main() {
int n, m;
cin >> n >> m;
vector<pair<int, int>> arr(n);
for(auto &[v, s] : arr)
cin >> s >> v;
sort(arr.begin(), arr.end());
vector<int> brr(m);
for(int &a : brr)
cin >> a;
sort(brr.begin(), brr.end());
vector<int> ans(m);
for(const auto &[_, s] : arr) {
for(int i = m - 1; ~i; i--) {
if(brr[i] < s)
break;
if(i)
ans[i] = max(ans[i - 1] + 1, ans[i]);
else
ans[i] = 1;
}
}
cout << ans.back() << '\n';
}
