void setup()
{
  int i ,j;
 volatile char *dirf, *dirk,*dira,*dirc;
volatile char *outf, *ink,*outa,*outc;
*dirf = 0x30, *dirk=0x107,dira=0x21,*dirc=0x27;
outf=0x31; ink=0x106;outa=0x22,*outc=0x28;
*dirf=0x0F; *dirk=0x00 ,*dira=0x0F,*dirc=0x0F;/// setting as the output port f & input is on k port

while(1){
for( i=0;i<4;i++)
  *outf=1<<i;
  *outa=*ink; 
  if(*ink !=0)
  *outc=1<<i;
    for( j =0;j<200000;j++ );
    *outc=0;
  

}
}