/**
____ ____ ____ ____ ____ ____
||l |||e |||i |||n |||a |||d ||
||__|||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|/__\|
**/
#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
const int maxn = 1e5 + 10;
struct picture
{
int s, v;
}p[maxn];
bool cmp(picture p1, picture p2)
{
if (p1.s < p2.s)
return true;
if (p1.s > p2.s)
return false;
return p1.v < p2.v;
}
int n, m, c[maxn], used[maxn], dp[maxn];
void solve()
{
cin >> n >> m;
for (int i = 1; i <= n; i ++)
{
cin >> p[i].s >> p[i].v;
}
for (int i = 1; i <= m; i ++)
cin >> c[i];
sort(c + 1, c + m + 1);
sort(p + 1, p + n + 1, cmp);
///cout << check(2) << endl;
///return;
int ans = 0;
for (int i = n; i > 0; i --)
{
int mx = 0;
for (int j = n; j > i; j --)
{
if (p[j].v >= p[i].v)
mx = max(mx, dp[j]);
}
mx ++;
mx = min(mx, m);
while(mx > 0 && c[m - mx + 1] < p[i].s)
mx --;
dp[i] = mx;
ans = max(ans, dp[i]);
}
cout << ans << endl;
}
int main()
{
solve();
return 0;
}
