import java.util.Scanner;
class Percolation
{
static int grid[];
public static int root(int i)
{
while(i!=grid[i])
{
grid[i]=grid[grid[i]];
i=grid[i];
}
return i;
}
public static boolean connected(int a,int b)
{
if(root(a)==root(b))
return true;
else
return false;
}
public static void union(int a,int b)
{
int root_a=root(a);
int root_b=root(b);
grid[root_a]=root_b;
}
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
System.out.print("Enter the size of grid: ");
int n=in.nextInt();
grid=new int[n*n+2];
int count=1;
for(int i=1;i<n*n+1;i++)
grid[i]=count++;
final int n_sq=n*n;
final int last=n_sq+1;
grid[last]=last;
int num1,num2;
for(int i=1;i<n+1;i++)
{
union(i,0);
union(last-i,last);
