#define L1 2
#define L2 3
#define L3 4
#define L4 5
#define C1 6
#define C2 7
#define C3 8
#define C4 9

void setup() {
    // to complete
}

void loop() {
    // 1
    digitalWrite(C1, HIGH);
    digitalWrite(L1, HIGH);

    delay(100);

    digitalWrite(C1, LOW);
    digitalWrite(L1, LOW);

    delay(100);

    // #
    digitalWrite(C3, HIGH);
    digitalWrite(L4, HIGH);
}