#include <bits/stdc++.h>
using namespace std;
#define int long long
#define inf 0x3F3F3F3F
vector<int> st;
void make(int l, int r, int x, int ind, int val)
{
if (l + 1 == r)
{
st[x] = max(st[x], val);
return;
}
int mid = (l + r) >> 1;
if (ind < mid) make(l, mid, 2*x + 1, ind, val);
else make(mid, r, 2*x + 2, ind, val);
st[x] = max(st[2*x + 1], st[2*x + 2]);
}
int get(int l, int r, int x, int lx, int rx)
{
if (l >= rx || r <= lx) return 0;
if (l >= lx && r <= rx) return st[x];
int mid = (l + r) >> 1;
return max(get(l, mid, 2*x + 1, lx, rx), get(mid, r, 2*x + 2, lx, rx));
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(nullptr);
int n, m, sz = 1;
cin >> n >> m;
int b[m];
array<int, 2> a[n];
for (array<int, 2> &x : a) cin >> x[1] >> x[0];
for (int &i : b) cin >> i;
sort(a, a + n, greater<array<int, 2>> ()), sort(b, b + m);
int res = 0;
for (array<int, 2> &x : a)
{
if (x[1] <= b[m - res - 1])
{
res++;
if (res == m) break;
}
}
cout << res << '\n';
}
