char chars[11] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K'};
int pins[13] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13};

void setup() {
  Serial.begin(9600);
  Serial.println(chars);
  for(int i = 0; i <= 12; i++){
    pinMode(pins[i], OUTPUT);
  }
}

void loop() {
  for(int i = 0; i <= 12; i++){
    digitalWrite(pins[i], HIGH);
    delay(500);
    digitalWrite(pins[i], LOW);
  }
}