#include <bits/stdc++.h>
#define MAXN 1010
#define mp make_pair
using namespace std;
typedef pair < int, int > ii;
int n, m, c[MAXN], dp[MAXN][MAXN];
ii phot[MAXN];
inline int func(int u, int ini)
{
if(u >= n or ini >= m) return 0;
if(dp[u][ini] != -1) return dp[u][ini];
int naop = func(u+1, ini);
int pega;
int i = ini, f = m-1, r = -1;
while(i <= f)
{
int meio = (i+f)/2;
if(c[meio] >= phot[u].second)
{
r = meio;
f = meio - 1;
}
else i = meio+1;
}
if(r == -1) pega = 0;
else pega = func(u+1, r+1) + 1;
return dp[u][ini] = max(pega, naop);
}
int main()
{
cin >> n >> m;
memset(dp, -1, sizeof dp);
for(int i = 0 ; i < n ; i++)
{
cin >> phot[i].second >> phot[i].first;
}
for(int i = 0 ; i < m ; i++)
{
cin >> c[i];
}
sort(c, c+m);
sort(phot, phot+n);
int r = func(0, 0);
cout << r << endl;
}
