int sensor=A0;
int LED = 5;
char* pass;
char* password = {"1234"};
void setup() {
  Serial.begin(9600);
  pinMode(LED, OUTPUT);

  Serial.println("Enter your password:");
  Serial.readBytes(pass, 4);
}
void loop() {
  int value = analogRead(sensor);
  int x; //x is the line between water and air value
  if (value > x) {

    digitalWrite(LED, HIGH);
    if (!(strcmp(pass, password))) {
      digitalWrite(LED, LOW);
    }
  }
  else{
   digitalWrite(LED, LOW);
  }

}