#include<cstdio>
//#include<cmath>
//#include<cstdlib>
#define fin "reuniune.in"
#define fies "reuniune.out"
#define maxdim 1000000
using namespace std;
int x[maxdim],y[maxdim],i,j,x1,y1,x0,y0,minx,maxx,miny,maxy,l1,l2,aria;
int main()
{
    for(i=0;i<maxdim;i++)
    {
        x[i]=0;
        y[i]=0;
    }
    freopen(fin,"r",stdin);

    miny=minx=maxdim;maxy=maxx=0;
    for(i=1;i<=3;i++)
    {scanf("%d %d %d %d",&x1,&y1,&x0,&y0);
    l1=(x1>x0)?x1:x0;
    if(maxx<l1)maxx=l1;
    l2=(x1<x0)?x1:x0;
    if(minx>l2)minx=l2;
    for(i=l2;i<=l1;i++)
    x[i]=1;
    l1=(y1>y0)?y1:y0;
    if(maxy<l1)maxy=l1;
    l2=(y1<y0)?y1:y0;
    if(miny>l2)miny=l2;
    for(i=l2;i<=l1;i++)
    y[i]=1;}
    aria=0;
    for(i=minx;i<=maxx;i++)
    for(j=miny;j<=maxy;j++)
    {
        aria=aria+x[i]*y[j];
    }
    freopen(fies,"w",stdout);
    printf("%d",aria);
    return 0;
}