int a=2;
int b=3;
int c=4;
void setup() {
  // put your setup code here, to run once:
pinMode(a, OUTPUT);
pinMode(b, OUTPUT);
pinMode(c, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(a,1);
delay(1000);
digitalWrite(a,0);
delay(1000);
digitalWrite(b,1);
delay(1000);
digitalWrite(b,0);
delay(1000);
digitalWrite(c,1);
delay(1000);
digitalWrite(c,0);
delay(1000);

}