L - Black-and-White Cube 简单构造

L - Black-and-White Cube

Time Limit:1000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u

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Appoint description:  System Crawler  (2013-08-06)

Description

You are given a cube of size k × k × k, which consists of unit cubes. Two unit cubes are considered neighbouring, if they have common face.

Your task is to paint each of k³ unit cubes one of two colours (black or white), so that the following conditions must be satisfied:

 

• each white cube has exactly 2 neighbouring cubes of white color;
• each black cube has exactly 2 neighbouring cubes of black color.

 

Input

The first line contains integer k(1 ≤ k ≤ 100), which is size of the cube.

Output

Print -1 if there is no solution. Otherwise, print the required painting of the cube consequently by layers. Print a k × k matrix in the firstk lines, showing how the first layer of the cube should be painted. In the following k lines print a k × k matrix — the way the second layer should be painted. And so on to the last k-th layer. Note that orientation of the cube in the space does not matter.

Mark a white unit cube with symbol "w" and a black one with "b". Use the format of output data, given in the test samples. You may print extra empty lines, they will be ignored.

Sample Input

Input

1

Output

-1

Input

2

Output

bb
ww

bb
ww

 

 

int main() 
{
    //freopen("in.txt","r",stdin);
    int k;
    while(cin>>k)
    {
        if(k%2)
        {
            cout<<-1<<endl;
            continue;
        }

        repf(i,1,k/2)//i layout
        {
            if(i%2 == 0)
            {
                repf(j,1,k)//j column
                {
                    repf(a,1,k/2)
                    {
                        if(j%2)
                        {
                            if(a%2)
                                cout<<"bb";
                            else
                                cout<<"ww";
                        }else
                        {
                            if(a%2==0)
                                cout<<"bb";
                            else
                                cout<<"ww";
                        }
                    }
                    cout<<endl;
                }
                cout<<endl;
                repf(j,1,k)//j column
                {
                    repf(a,1,k/2)
                    {
                        if(j%2)
                        {
                            if(a%2)
                                cout<<"bb";
                            else
                                cout<<"ww";
                        }else
                        {
                            if(a%2==0)
                                cout<<"bb";
                            else
                                cout<<"ww";
                        }

                    }
                    cout<<endl;
                }
                cout<<endl;
            }else
            {
                 repf(j,1,k)
                 {
                     repf(a,1,k/2)
                     {
                         if(j%2==0)
                         {
                             if(a%2)
                                 cout<<"bb";
                             else
                                 cout<<"ww";
                         }else
                         {
                             if(a%2==0)
                                 cout<<"bb";
                             else
                                 cout<<"ww";
                         }
                     }
                     cout<<endl;
                 }
                 cout<<endl;
                 repf(j,1,k)
                 {
                     repf(a,1,k/2)
                     {
                         if(j%2==0)
                         {
                             if(a%2)
                                 cout<<"bb";
                             else
                                 cout<<"ww";
                         }else
                         {
                             if(a%2==0)
                                 cout<<"bb";
                             else
                                 cout<<"ww";
                         }
                     }
                       cout<<endl;
                 }
                   cout<<endl;
            }
        }
    }
    return 0;
}