#define LED1 2
#define LED2 4
int b =5;


void setup() {
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(b,INPUT);

}

void loop() {
    int p=digitalRead(b);
    if(p==LOW)
    {
  digitalWrite(LED1, HIGH);
  digitalWrite(LED2,HIGH);
  delay(500);
    }
    else
    {
  digitalWrite(LED2,LOW);
  digitalWrite(LED1, LOW);
  delay(500);
    }
}