#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define p(x,y) pair<ll,ll>(x,y)
#define BIT(i,x) ((x>>i)&1)
#define MASK(x) (1<<x)
#define ld long double
#define __builtin_popcount __builtin_popcountll
#define pll pair<ll,ll>
template<class T1,class T2>
bool maximize(T1 &x,const T2 &y)
{
if(x<y)
{
x=y;
return 1;
}
return 0;
}
template<class T1,class T2>
bool minimize(T1 &x,const T2 &y)
{
if(x>y)
{
x=y;
return 1;
}
return 0;
}
void online()
{
std::ios_base::sync_with_stdio(0);
cin.tie(0);
#ifdef thuc
freopen("input.INP","r",stdin);
freopen("output.OUT","w",stdout);
#else
#endif
}
const ll N=1e5+10;
ll n,m;
pll a[N];
ll b[N];
int main()
{
online();
cin>>n>>m;
for(int i=0;i<n;i++)
{
cin>>a[i].se>>a[i].fi;
}
sort(a,a+n,greater<pll>());
for(int i=0;i<m;i++)
{
cin>>b[i];
}
sort(b,b+m,greater<ll>());
ll ans=0;
for(int i=0;i<n;i++)
{
if(a[i].se<=b[ans])
{
ans++;
}
}
cout<<ans;
}
