int r1 = 25, Y = 26, g1 = 27;
int r2 = 23, y2 = 22, g2 = 21;

void setup() {
  Serial.begin(115200);
  pinMode(r1, OUTPUT);
  pinMode(Y, OUTPUT);
  pinMode(g1, OUTPUT);
  pinMode(r2, OUTPUT);
  pinMode(y2, OUTPUT);
  pinMode(g2, OUTPUT);
}

void loop() {
  digitalWrite(r2, LOW);
  digitalWrite(g1, LOW);
  digitalWrite(r1, HIGH);
  digitalWrite(g2, HIGH);
  delay(2500); 
  digitalWrite(r1, LOW);
  digitalWrite(g2, LOW);
  digitalWrite(Y, HIGH);
  digitalWrite(y2, HIGH);
  delay(2500);
  digitalWrite(Y, LOW);
  digitalWrite(y2, LOW);
  digitalWrite(r2, HIGH);
  digitalWrite(g1, HIGH);
  delay(2500);
}