#include <fstream>
using namespace std;
ifstream f("inundatii.in");
ofstream g("inundatii.out");

long long n,x,y,z,S;

int main()
{
    int i;
    f>>n;
    if(n==1){
        g<<"0\n";
        return 0;}
    for(i=1;i<=n/2;i++){
        f>>x>>y>>z;
        S+=x+y+z;}
    f>>x>>y>>z;
    if(n%2==0)
        S-=(x+y+z);
    for(i=n/2+2;i<=n;i++){
        f>>x>>y>>z;
        S-=(x+y+z);}
    if(n%2)
        S+=3*(n/2)*(n/2+1);
    else
        S+=3*(n*n/4);
    g<<S<<'\n';
    f.close();
    g.close();
    return 0;
}