Simple Traffic Light Controller

//Modified by ProfessorHulk

int R = 5;
int Y = 6;
int G = 7;

void setup()
{
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
}

void loop()
{
  //Red light starts glowing:
  digitalWrite(R, HIGH);
  delay(3000);
  digitalWrite(R, LOW);
  delay(1000);
  
  //Yellow light starts to glow:
  digitalWrite(Y, HIGH);
  delay(3000);
  digitalWrite(Y,LOW);
  delay(1000);
  
  //Green Light starts t0 glow:
  digitalWrite(G, HIGH);
  delay(1000);
  digitalWrite(G, LOW);
  delay(500);
  digitalWrite(G, HIGH);
  delay(1000);
  digitalWrite(G, LOW);
  delay(500);
  digitalWrite(G, HIGH); // IT FLICKERS TWICE and then blinks continuously
  delay(3000);
  digitalWrite(G, LOW);
  delay(500);
  
  
}