int ledr=2;
int ledg=4;
int ledy=7;
void setup() {
  // put your setup code here, to run once:
pinMode(ledr,OUTPUT);
pinMode(ledg,OUTPUT);
pinMode(ledy, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(ledr,HIGH);
delay(2000);
digitalWrite(ledr,LOW);
delay(0);

digitalWrite(ledg, HIGH);
delay(2000);
digitalWrite(ledg,LOW);
delay(0);

digitalWrite(ledy, HIGH);
delay(2000);
digitalWrite(ledy,LOW);
delay(0);
}