int led1 = 14;
int led2 = 27;
int led3 = 26;
int led4 = 25;
char input;

void setup() {
  Serial.begin(115200);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
}

void loop() {
  while (Serial.available()) {
    input = Serial.read();
    Serial.println(input);
  }
  if (input == 'a') {
    digitalWrite(led1, HIGH);
  }
  if (input == 'b') {
    digitalWrite(led1, LOW);
  }
  if (input == 'c') {
    digitalWrite(led2, HIGH);
  }
  if (input == 'd') {
    digitalWrite(led2, LOW);
  }
  if (input == 'e') {
    digitalWrite(led3, HIGH);
  }
  if (input == 'f') {
    digitalWrite(led3, LOW);
  }
  if (input == 'g') {
    digitalWrite(led4, HIGH);
  }
  if (input == 'h') {
    digitalWrite(led4, LOW);
  }
}