const int buttonPin = 2; 
const int relayPin = 3;  
bool latchState = false; 

void setup() {
  pinMode(buttonPin, INPUT_PULLUP); 
  pinMode(relayPin, OUTPUT);         
}

void loop() {
  if (digitalRead(buttonPin) == LOW) { 
    latchState = !latchState;           
    digitalWrite(relayPin, latchState); 
    delay(500);                          
  }
}