#include<bits/stdc++.h>
using namespace std;
//_______________________________________________
const int N=1e5+2;
struct bg
{
long long val, sz, idx;
};
long long n, m;
bg a[N];
long long b[N];
//_______________________________________________
bool cmp1(bg x, bg y)
{
return x.val<y.val;
}
bool cmp2(bg x, bg y)
{
return x.sz<y.sz;
}
namespace sub2
{
bool check()
{
return (n<=1000 and m<=1000);
}
long long node[1002][4*1002];
void update(int vitri, int goc, int l, int r, int idx, long long value)
{
if(idx<l or idx>r)return ;
if(l==r)
{
node[vitri][goc]=max(node[vitri][goc], value);
return;
}
int mid=(l+r)>>1;
update(vitri, goc*2, l, mid, idx, value);
update(vitri, goc*2+1, mid+1, r, idx, value);
node[vitri][goc]=max(node[vitri][goc*2], node[vitri][goc*2+1]);
}
long long get(int vitri, int goc, int l, int r, int trai, int phai)
{
if(trai>phai)return 0;
if(l>phai or r<trai)return 0;
if(trai<=l and r<=phai)return node[vitri][goc];
int mid=(l+r)>>1;
return max(get(vitri, goc*2, l, mid, trai, phai), get(vitri, goc*2+1, mid+1, r, trai, phai));
}
void solve()
{
memset(node, 0, sizeof node);
long long ans=0;
for(int j=1; j<=m; j++)
{
for(int i=1; i<=n; i++)
{
if(a[i].sz<=b[j])
{
long long temp=0;
if(a[i].idx>1)
temp=get(j-1, 1, 1, n, 1, a[i].idx-1);
update(j, 1, 1, n, a[i].idx, temp+1);
ans=max(ans, temp+1);
}
}
}
cout<<ans;
}
}
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>m;
for(int i=1; i<=n; i++)
{
cin>>a[i].sz>>a[i].val;
}
for(int i=1; i<=m; i++)cin>>b[i];
sort(b+1, b+m+1);
sort(a+1, a+n+1, cmp1);
for(int i=1; i<=n; i++)a[i].idx=i;
sort(a+1, a+n+1, cmp2);
if(sub2::check())sub2::solve();
return 0;
}
