/***************************************************
 * Author    : CS Developers
 * Author URI: https://www.comscidev.com
 * Facebook  : https://www.facebook.com/CSDevelopers
 ***************************************************/
 
#include<stdio.h>

int main()
{
	int octagonSize;
	int r, s, i;
	
    printf("  Enter number for Octagon size : ");
	scanf("%d", &octagonSize);
   	
   	for(r=0; r<octagonSize; r++)
   	{
   		for(s=0; s<=octagonSize-r; s++){
   			printf(" ");
		}
		
		for(i=0; i<octagonSize; i++){
			if(r==0){
				printf("* ");
			}
			else if(r>0 && octagonSize == 2){
				printf("*");
				for(s=0; s<(octagonSize*2-3)+r*2; s++){
					printf(" ");
				}				
			}
			else if(r>0){
				if(i==0 || i == octagonSize-1){
					printf("*");	
				}else{
					for(s=0; s<(octagonSize*2-3)+r*2; s++){
						printf(" ");
					}
					i=octagonSize-2;	
				}
			}
		}
		printf("\n");
	}
	
	for(r=0; r<octagonSize; r++)
	{
		for(s=0; s<=octagonSize*4-3; s++){
			if(s==0 || s == octagonSize*4-3){
				printf(" *");
			}else{
				printf(" ");	
			}
		}
		printf("\n");
	}
	
	for(r=0; r<octagonSize; r++)
   	{
   		for(s=0; s<=r+1; s++){
   			printf(" ");
		}
		
		for(i=0; i<octagonSize; i++){
			if(r==octagonSize-1){
				printf("* ");
			}else if(r==0 && octagonSize == 2){
				printf("*");
				for(s=0; s<(octagonSize*4-5)-r*2; s++){
					printf(" ");
				}				
			}
			else if(r>=0){
				if(i==0 || i == octagonSize-1){
					printf("*");	
				}else{
					for(s=0; s<(octagonSize*4-5)-r*2; s++){
						printf(" ");
					}
					i=octagonSize-2;
				}
			}
		}
		printf("\n");
	}
	
	return 0;
}