void   main()   
  {   
       HANDLE a;   
       a=GetStdHandle(STD_OUTPUT_HANDLE);
       COORD   stps[64]={0};
       char sText[64]={0};
       int Ncount=0;
       int Ntime=0;
       int Num=0;
       srand(time(NULL));
       for(int i=0;i<5;i++)
       {
            sText[i]=rand()%26+'a';
            stps[i].X = rand()%80;
            Ncount++;
       }
       while(1)
       {
      
            if (Ntime >= 2000)
            {
                Ntime  -= 2000;
                sText[Ncount]=rand()%26+'a';
                stps[Ncount].X=rand()%80;
                stps[Ncount].Y=0;
               Ncount++;
            }
            for (int j=0;j<Ncount;j++)
            {
                SetConsoleCursorPosition(a,stps[j]);
                printf("%c", sText[j]);
            }
             Num++;
          int c=Num/10;

       switch(c)
       {
        case 0 : Sleep(1000);break;
        case 1 : Sleep(700);break;
        case 2 : Sleep(500);break;     
        case 3 : Sleep(300);break;
        default: Sleep(200);break;
       }
            Ntime  +=700;

             for (j=0;j< Ncount;j++)   
            {
                SetConsoleCursorPosition(a,stps[j]);
                printf("%c", ' ');
                stps[j].Y++;
                if (stps[j].Y>24)
                {
                    if (j==Ncount-1)
                    {
                        Ncount--;
                    }
                    else
                    {
                        for (int k=j;k<Ncount-1;k++)
                        {
                            sText[k] = sText[k+1];
                            stps[k].X = stps[k+1].X;
                            stps[k].Y = stps[k+1].Y;
                        }
                    }
                }
            }
        
       }

}