// C++ code

//

void setup()

{

pinMode(4, OUTPUT);

pinMode(3, OUTPUT);

}

void loop()

{

digitalWrite(4,1);

digitalWrite(3,0);

delay(1000); // Wait for 1000 millisecond(s)

digitalWrite(3,1);

digitalWrite(4,0);

delay(1000); // Wait for 1000 millisecond(s)

}