#define b1 17 
#define b2 5  
#define rly 4 

void setup() {
  pinMode(b1, INPUT);
  pinMode(b2, INPUT);
  pinMode(rly, OUTPUT);

  digitalWrite(rly, LOW); 
}

void loop() {
  if (digitalRead(b1) == LOW) {
    digitalWrite(rly, HIGH);
    delay(300);
  }

  if (digitalRead(b2) == LOW) { 
    digitalWrite(rly, LOW); 
    delay(300); 
  }
}