#include <fstream.h>
#define dim 100//25001
long v[3][dim],n,nn;
unsigned long dist;

int main()
{long i,j,x,y,z;
ifstream f("inundatii.in");
f>>n;
nn=n/2;
for(i=1;i<=nn;i++)
 f>>v[0][i]>>v[1][i]>>v[2][i];
if(n%2)
 f>>x>>y>>z;//f>>v[0][i]>>v[1][i]>>v[2][i];
i--;
while(i)
 {f>>x>>y>>z;
  dist+=2*((v[0][i]-x+1)/2+(v[1][i]-y+1)/2+(v[2][i]-z+1)/2);
  i--;
 }
f.close();
ofstream g("inundatii.out");
g<<dist<<'\n';
g.close();
return 0;
}