#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 1;
int n, m, x[N], C[N];
pair<int, int> a[N];
int b[N];
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
memset(b, 0xc0, 4 * N);
cin >> n >> m;
for (int i = 1; i <= n; i++) cin >> a[i].second >> a[i].first;
sort(a + 1, a + n + 1);
for (int i = 1; i <= m; i++) cin >> C[i];
sort(C + 1, C + m + 1);
for (int i = 1; i <= n; i++) x[i] = lower_bound(C + 1, C + m + 1, a[i].second) - C - i;
sort(x + 1, x + n + 1);
int l = 1, r = n;
while (l <= r) {
int M = (l + r) >> 1;
if (m - M >= x[M]) l = M + 1;
else r = M - 1;
}
cout << r;
}
