import java.io.*;

class Main
{
    public static void main (String[ ] args) throws Exception
    {
        BufferedReader br = new BufferedReader (new InputStreamReader (System.in));
        StringBuffer sb = new StringBuffer();
        
        while(true)
        {
            String[] strAry = (br.readLine()).split(" ");
            int h = Integer.parseInt(strAry[0]);
            int w = Integer.parseInt(strAry[1]);
        
            if(0 == h & 0 == w)
            {
                break;
            }

            for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        System.out.print(sb);
    }
} import java.io.*; io.* java class Main
{
    public static void main (String[ ] args) throws Exception
    {
        BufferedReader br = new BufferedReader (new InputStreamReader (System.in));
        StringBuffer sb = new StringBuffer();
        
        while(true)
        {
            String[] strAry = (br.readLine()).split(" ");
            int h = Integer.parseInt(strAry[0]);
            int w = Integer.parseInt(strAry[1]);
        
            if(0 == h & 0 == w)
            {
                break;
            }

            for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        System.out.print(sb);
    }
} Main public static void main (String[ ] args) throws Exception
    {
        BufferedReader br = new BufferedReader (new InputStreamReader (System.in));
        StringBuffer sb = new StringBuffer();
        
        while(true)
        {
            String[] strAry = (br.readLine()).split(" ");
            int h = Integer.parseInt(strAry[0]);
            int w = Integer.parseInt(strAry[1]);
        
            if(0 == h & 0 == w)
            {
                break;
            }

            for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        System.out.print(sb);
    } main {
        BufferedReader br = new BufferedReader (new InputStreamReader (System.in));
        StringBuffer sb = new StringBuffer();
        
        while(true)
        {
            String[] strAry = (br.readLine()).split(" ");
            int h = Integer.parseInt(strAry[0]);
            int w = Integer.parseInt(strAry[1]);
        
            if(0 == h & 0 == w)
            {
                break;
            }

            for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        System.out.print(sb);
    } BufferedReader br = new BufferedReader (new InputStreamReader (System.in)); br new BufferedReader (new InputStreamReader (System.in)) StringBuffer sb = new StringBuffer(); sb new StringBuffer() while(true)
        {
            String[] strAry = (br.readLine()).split(" ");
            int h = Integer.parseInt(strAry[0]);
            int w = Integer.parseInt(strAry[1]);
        
            if(0 == h & 0 == w)
            {
                break;
            }

            for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        } true {
            String[] strAry = (br.readLine()).split(" ");
            int h = Integer.parseInt(strAry[0]);
            int w = Integer.parseInt(strAry[1]);
        
            if(0 == h & 0 == w)
            {
                break;
            }

            for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        } String[] strAry = (br.readLine()).split(" "); strAry (br.readLine()).split(" ") (br.readLine()).split (br.readLine()) br.readLine br " " int h = Integer.parseInt(strAry[0]); h Integer.parseInt(strAry[0]) Integer.parseInt Integer strAry[0] strAry 0 int w = Integer.parseInt(strAry[1]); w Integer.parseInt(strAry[1]) Integer.parseInt Integer strAry[1] strAry 1 if(0 == h & 0 == w)
            {
                break;
            } 0 == h & 0 == w 0 == h 0 h 0 == w 0 w {
                break;
            } break; for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            } int i = 0; int i = 0; i 0 i < h i h i++ i++ i {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            } {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            } for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                } int j = 0; int j = 0; j 0 j < w j w j++ j++ j {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                } {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                } if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    } 0 == ((i + j) % 2) 0 ((i + j) % 2) (i + j) i j 2 {
                        sb.append("#");
                    } sb.append("#") sb.append sb "#" {
                        sb.append(".");
                    } sb.append(".") sb.append sb "." sb.append("\n") sb.append sb "\n" sb.append("\n") sb.append sb "\n" System.out.print(sb) System.out.print System.out System System.out sb String[ ] args args
import java.io.*;

class Main
{
    public static void main (String[ ] args) throws Exception
    {
        BufferedReader br = new BufferedReader (new InputStreamReader (System.in));
        StringBuffer sb = new StringBuffer();
        
        while(true)
        {
            String[] strAry = (br.readLine()).split(" ");
            int h = Integer.parseInt(strAry[0]);
            int w = Integer.parseInt(strAry[1]);
        
            if(0 == h & 0 == w)
            {
                break;
            }

            for(int i = 0; i < h; i++)
            {
                for(int j = 0; j < w; j++)
                {
                    if(0 == ((i + j) % 2))
                    {
                        sb.append("#");
                    }
                    else
                    {
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        System.out.print(sb);
    }
}