#include <fstream>

using namespace std;
ifstream f("bal.in");
ofstream g("bal.out");
int a,b,x,y,mac,i,j,v[1000001],p,u[1000001],mac1,mac2,my;
int main()
{
    f>>a>>b;
    for(i=1;i<=a+b;i++)
    {
        f>>x>>y;
        if(i<=a)
        {
            for(j=x;j<=y;j++)
                v[j]=v[j]+1;
        }
        if(i>a)
        {
            for(p=x;p<=y;p++)
                u[p]=u[p]+1;
        }
        my=(y>my?y:my);
    }
    mac1=0;
    for(i=1;i<=my;i++)
    {
        if(v[i]<u[i]) mac=v[i];
            else mac=u[i];
        if (mac>mac1) mac1=mac;
    }
    g<<mac1;
    return 0;
}