Description

A fractal is an object or quantity that displays self-similarity, in a somewhat technical sense, on all scales. The object need not exhibit exactly the same structure at all scales, but the same "type" of structures must appear on all scales.

A Sierpinski fractal is defined as below:

• A Sierpinski fractal of degree 1 is simply

  @

• A Sierpinski fractal of degree 2 is

  @@@

• If using B(n-1) to represent the Sierpinski fractal of degree n-1, then a Sierpinski fractal of degree n is defined recursively as following

  B(n-1)B(n-1)B(n-1)

  Your task is to draw a Sierpinski fractal of degree n.

Input

The input consists of several test cases. Each line of the input contains a positive integer n which is no greater than 10. The last line of input is an integer 0 indicating the end of input.

Output

For each test case, output the Sierpinski fractal using the '@' notation. Print a blank line after each test case.Don't output any trailing spaces at the end of each line, or you may get a PE!

Sample Input

120

Sample Output

@

@
@@

瑞神的程式碼，自己太水了，剛學會遞迴。。。。

#include<cstdio>
#include<cstring>
using namespace std;
const int inf=0x3f3f3f3f;
const int maxn=1030;
char g[maxn][maxn];
void draw(int n,int l1,int l2,int r1,int r2){
    if(n==1){
        g[l1][r1]='@';return;
    } 
    int k=1<<(n-2);
    draw(n-1,l1,l1+k,r1,r1+k);
    draw(n-1,l2-k,l2,r1,r1+k);
    draw(n-1,l2-k,l2,r2-k,r2);
    return;
}
int main(){
    int n;
    while(~scanf("%d",&n)&&n){
        memset(g,' ',sizeof(g));
        draw(n,0,1<<(n-1),0,1<<(n-1));
        int k=1<<(n-1);
        for(int i=0;i<k;++i){
            for(int j=k-1;j>=0;--j)
                if(g[i][j]=='@') {
                    g[i][j+1]=0;break;
                } puts(g[i]);
        } puts("");
    }
    return 0;
}