void setup()
{
  volatile char *dirf,*outf;
  volatile char *dirk,*ink;
  dirf=0x30; outf=0x31;
  dirk=0x107; ink=0x106;
  *dirf=0xFF; *ink=0x00;
  volatile char switches;
  volatile long arr[]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
  volatile long arr1[]={0,1,2,4,8,16,32,64,128};
  unsigned long sum=0,count=0;
  volatile long i,j,k,l,n,m,p,q;
  while(1)
  {
    if(count==4)
    {
      sum=(sum/10)+(sum%10);// making sum as single digit
      *outf=arr[sum];//output
      sum=0;// again put sum=0 to again add new digits
      count=0;//again put count=0 to again count switches
    }
    else
    {
      switches=*ink;
      for(i=1;i<=8;i++)
      {
        if((switches & arr1[i]) == arr1[i])
        {
          sum=sum+i;//sum of digits
          count++;// count for switch press
          for(j=0;j<=50000;j++);// delay for debouncing
        }
      }
    }
  }
}

void loop()
{

}