void setup() {
  // put your setup code here, to run once:
  volatile char *dr,*dr1,x;
  dr=0x30;
  dr1=0x107;
  *dr=0xff;
  *dr1=0x00;


}

void loop() {
  // put your main code here, to run repeatedly:

volatile char *in,*in1,x;
in=0x31;
in1=0x106;
x=*in1;
if((x)==0x01)
*in=0x03;
else
*in=0x00;

}