void setup() {
  Serial.begin(9600);
  // put your setup code here, to run once:
  pinMode(1,INPUT);
  pinMode(16,INPUT);

  attachInterrupt(1,button1Pressed,RISING);
  attachInterrupt(16,button2Pressed,RISING);
}

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

}


void button1Pressed(){
  Serial.print('a');
  delay(100);
}


void button2Pressed(){
  Serial.print('b');
  delay(100);
}