import java.io.*;

public class MatrixCategory {

public static void main() throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

System.out.println("ENTER THE SIZE OF MATRIX= ");

int n = Integer.parseInt(br.readLine());

int val;

int lower = 1, upper = 1;

System.out.println("ENTER THE ELEMENTS = ");

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

val = Integer.parseInt(br.readLine());

if (i > j && val != 0)

upper = 0;

if (i < j && val != 0)

lower = 0;

}

}

if (upper == 1 && lower == 1)

System.out.println("2");

else if (upper == 1)

System.out.println("1");

else if (lower == 1)

System.out.println("-1");

else

System.out.println("0");

}

}