#include<bits/stdc++.h>
#define fi first
#define se second
#define FOR(i, k, n) for(int i = k; i <= n; i++)
#define FOR1(i, k, n) for(int i = k; i >= n; i--)
#define pb push_back
#define fastio ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define vi vector<int>
#define pii pair<int, int>
#define vii vector<pii>
#define ll long long
#define vll vector<ll>
#define pll pair<ll, ll>
#define re return 0
#define mii map<int, int>
#define input "SORT.inp"
#define output "SORT.out"
#define rf freopen(input, "r", stdin); freopen(output, "w", stdout)
using namespace std;
const int maxn = 1e5 + 5;
const int mod = 1e9 + 7;
const int base = 998244353;
const int base1 = 31;
const int SZ = 320;
const ll INF = 1e18;
void add(int &a, int b)
{
a += b;
if(a >= mod) a -= mod;
if(a < 0) a += mod;
}
mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r)
{
return uniform_int_distribution<int>(l, r) (rd);
}
pii a[maxn];
int b[maxn];
int main()
{
fastio;
int n, m;
cin >> n >> m;
FOR(i, 1, n)
cin >> a[i].se >> a[i].fi;
FOR(i, 1, m)
cin >> b[i];
sort(a + 1, a + 1 + n);
sort(b + 1, b + 1 + m);
reverse(a + 1, a + 1 + n);
reverse(b + 1, b + 1 + m);
int vt = 1, ans = 0;
FOR(i, 1, n)
{
if(vt > m)
break;
if(b[vt] >= a[i].se)
vt++, ans++;
}
cout << ans;
re;
}
