int sun=0;

void setup() {
pinMode(2, INPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
}

void loop() {
if (digitalRead(2 == HIGH && sun == 0) ){

digitalWrite(3, HIGH);
delay(1000);
digitalWrite(3, LOW);
delay(1000);
digitalWrite(4, HIGH);
delay(1000);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
sun += 1;
}
else if (digitalRead(2 == LOW && sun == 1)) {
sun = 0;
}

}

這樣應該可以了