remplissage matrice # et O

import java.util.*;
import java.io.*;
import java.math.*;
class Solution {

    public static void main(String args[])
    {
        Scanner in = new Scanner(System.in);
        int N = in.nextInt();
        char mat[][] = new char[N][N];
        int lh = 0, lb = N - 1, cg = 0, cd = N - 1;
        int max = N;
        char aff = 'O';
        while (cg <= N/2) {
            aff = reverseChar(aff);
            for (int i = 0+N-max; i < max; i++)  // lh
                mat[lh][i] = aff;

            for (int i = 0+N-max; i < max; i++)
                mat[lb][i] = aff;

            for (int i = 0+N-max; i < max; i++)
                mat[i][cg] = aff;

            for (int i = 0+N-max; i < max; i++)
                mat[i][cd] = aff;
            lh++;
            lb--;
            cg++;
            cd--;
            max--;
        }
        for (int i = 0; i < N; i++)
        {
            for (int j = 0; j < N; j++)
                System.out.print(mat[i][j]);
            System.out.println();
        }
    }

    public static char reverseChar(char x)
    {
        if(x == '#')
            return 'O';
        else
            return '#';
    }
}