const int led1 = 9; 
const int led2 = 10; 

void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
}

void loop() {
  digitalWrite(led1, HIGH); 
  delay(3000); 
  digitalWrite(led1, LOW); 
  digitalWrite(led2, HIGH);
  delay(5000); 
  digitalWrite(led2, LOW); 
}