bool time = false;
double startTime=millis();

void setup() {
  Serial.begin(9600);
  // put your setup code here, to run once:
  pinMode(1,INPUT);
  pinMode(16,INPUT);
  pinMode(9,OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  
  if (millis() > startTime+5000){
    time=true;
  }
  if (time == true){
    digitalWrite(9,HIGH);
    if (digitalRead(1) == HIGH){
      Serial.print('a');
      time=false;
      digitalWrite(9,LOW);
      startTime=millis();
    } else if (digitalRead(16) == HIGH){
      Serial.print('b');
      time=false;
      digitalWrite(9,LOW);
      startTime=millis();
    }
    
    
  }
}