const int buzzer=26;
const int led1=2;
const int led2=4;
const int led3=5;


void setup() {
 pinMode(buzzer, OUTPUT);
 pinMode(led1, OUTPUT);
 pinMode(led2, OUTPUT);
 pinMode(led3, OUTPUT);
}

void loop() {
  digitalWrite(led1, HIGH);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
  tone(buzzer, 291);
  delay(1000);
  digitalWrite(led1, LOW);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, LOW);
  tone(buzzer, 349);
  delay(1000);
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, HIGH);
  tone(buzzer, 493);
  delay(1000);
}