#include <bits/stdc++.h>
#define pb push_back
#define ppb pop_back
#define fi first
#define se second
#define mid ((x + y) / 2)
#define left (ind * 2)
#define right (ind * 2 + 1)
#define mp make_pair
#define timer ((double)clock() / CLOCKS_PER_SEC)
#define endl "\n"
#define spc " "
#define d1(x) cerr<<#x<<":"<<x<<endl
#define d2(x, y) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<endl
#define d3(x, y, z) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<" "<<#z<<":"<<z<<endl
#define fast_io() ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
using namespace std;
typedef long long int lli;
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<double, double> dd;
const int N = (int)(1e6 + 5);
const int LOG = (int)(20);
int n, m, ans, c[N];
ii p[N];
int main() {
fast_io();
// freopen("inp.in", "r", stdin);
cin >> n >> m;
for(int i = 1; i <= n; i++)
cin >> p[i].se >> p[i].fi;
for(int i = 1; i <= m; i++)
cin >> c[i];
sort(p + 1, p + n + 1);
sort(c + 1, c + m + 1);
int ind = m;
for(int i = n; i >= 1 && ind > 0; i--)
if(c[ind] >= p[i].se) {
ans++;
ind--;
}
cout << ans;
}
