int led1 = 19;
int led2 = 18;
int led3 = 5;
int led4 = 17;
char key = '0' ;
void setup() {
  pinMode(led1, OUTPUT); 
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  digitalWrite(led1, LOW); 
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
  digitalWrite(led4, LOW);
  Serial.begin(115200);
}
void loop() {
  if (Serial.available() > 0) {
    key = Serial.read();
    Serial.print("key : ");
    Serial.println(key);
  }
  if (key == '0') {
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    digitalWrite(led4, LOW);
  }
  if (key == '1') digitalWrite(led1, HIGH);
  if (key == '2') digitalWrite(led2, HIGH);
  if (key == '3') digitalWrite(led3, HIGH);
  if (key == '4') digitalWrite(led4, HIGH);
}