void setup()
{
  volatile char *dirf,*outf;
  volatile char *dirk,*outk;
  volatile char *dira,*outa;
  volatile char *dirc,*outc;
  dirf=0x30; outf=0x31;
  dirk=0x107; outk=0x108;
  dira=0x21; outa=0x22;
  dirc=0x27; outc=0x28;
  *dirf=0xFF; *dirk=0xFF;
  *dira=0xFF; *dirc=0xFF;
  volatile long arr[]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
  volatile long i,j,k,l,m;
  loop:while(1)
  {
    for(i=9;i>=0;i--)
    {
      for(j=9;j>=0;j--)
      {
        for(k=9;k>=0;k--)
        {
          for(l=9;l>=0;l--)
          {
            if(i>0)//to display from 9999 to 1000
            {
              *outf=arr[i];
              *outk=arr[j];
              *outa=arr[k];
              *outc=arr[l];
              for(m=0;m<=1000;m++);
            }
            else if(j>0)// to display from 999 to 100
            {
              *outf=0;
              *outk=arr[j];
              *outa=arr[k];
              *outc=arr[l];
              for(m=0;m<=10000;m++);
            }
            else if(k>0)// to display from 99 to 10
            {
              *outk=0;
              *outa=arr[k];
              *outc=arr[l];
              for(m=0;m<=10000;m++);
            }
            else//to display from 9 to 0
            {
              *outa=0;
              *outc=arr[l];
              for(m=0;m<=100000;m++);
            }
            if(i==0 && j==0 && k==0 && l==0)
            goto loop;
          }
        }
      }
    }
  }
}

void loop()
{
  
}