#include <iostream>
#include <fstream>

using namespace std;

ifstream in("imagine.in");
ofstream out("imagine.out");

const int nMax = 255;
bool a[nMax][nMax];
int n;
int rasp = 0;

void citire()
{
    in >> n;
    for(int i = 1; i <= n; ++i)
        for(int j = 1; j <= n; ++j)
            in >> a[i][j];
}

void rez(int startX, int startY, int stopX, int stopY)
{
    bool exista[2];
    exista[0] = false;
    exista[1] = false;
    for(int i = startX; i <= stopX; ++i)
        for(int j = startY; j <= stopY; ++j)
        {
            if(exista[0] && exista[1])
                break;
            exista[a[i][j]] = true;
        }
    if(exista[0] && exista[1])
    {
        int medX = (startX + stopX) / 2;
        int medY = (startY + stopY) / 2;
        rez(medX + 1, startY, stopX, medY);
        rez(startX, startY, medX, medY);
        rez(medX + 1, medY + 1, stopX, stopY);
        rez(startX, medY + 1, medX, stopY);
        rasp++;
    }
    else
        rasp += 2;
}

int main()
{
    citire();
    rez(1, 1, n, n);
    out << rasp;
    return 0;
}