int LED = 4;
int START = 25;
int STOP = 26;

void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);
  pinMode(START, INPUT);
  pinMode(STOP, INPUT);
  digitalWrite(LED, LOW);
  Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(STOP)==1)
  {
    digitalWrite(LED, LOW);
  }

  if (digitalRead(START)==1)
  {
    digitalWrite(LED, HIGH);
  }
}