#include<bits/stdc++.h>
using namespace std;
int a[200010][5]={0};
int b[200010]={0};
int main()
{
    freopen("dream.in","r",stdin);
    freopen("dream.out","w",stdout);
    int n,m,c,d,ans,i,j;
    cin>>n>>m;
    for(i=1;i<=n;i++)
    {
        cin>>a[i][1]>>a[i][2];
    }
    for(i=1;i<=m;i++)
    {
        cin>>b[i];
    }
    sort(b+1,b+m+1);
    for(i=1;i<=m;i++)
    {
        c=1000000010;d=0;
        for(j=1;j<=n;j++)
        {
            if(a[j][1]<=b[i]&&a[j][2]>=b[i]&&a[j][2]-b[i]<=c&&a[j][3]==0)
            {
                c=a[j][2]-b[i];
                d=j;
            }
        }
        if(d!=0)
        {
            a[d][3]=1;
            ans++;
        }
    }
    cout<<ans;
    return 0;
}