butterfly

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define INF 2000000000
#define fiMAX(x,y) (x>y?x:y)
#define fiMIN(x,y) (x>y?y:x)
/*
IN : 4
OUT :
*      *
**    **
***  ***
********
***  ***
**    **
*      *
*/
int main()
{
    int N;
    int i,j,k;
    int L,R;
    scanf("%d",&N);
    L=1;
    R=N*2;
    for(i=1; i<=N*2-1; i++)
    {
        for(j=1; j<=N*2; j++)
        {
            if(i<=N)
            {
                if(j<=L || R<=j) printf("*");
                else printf(" ");
            }
            else
            {
                if(j>L || R>j) printf("*");
                else printf(" ");
            }
        }
        L++;
        R--;
        printf("\n");
    }
    return 0;
}