DSA-lab4(a)-Queue

public class Main {
    public final int max = 4;
    public int[] arr = new int[max];
    public int f = -1;
    public int r = -1;

    public void enque(int data) {
        if (r == max - 1) {
            System.out.println("Overflow");
            return;
        }
        if (f == -1) {
            f = 0;
        }
        r++;
        arr[r] = data;
    }

    public void deque() {
        if (f == -1 || f > r) {
            System.out.println("Underflow");
            return;
        }

        if (f == r) {
          System.out.println("Last Remaining Element: " + arr[f]);
            f = -1;
            r = -1;
        } else {
         f++;
        }
    }

    public static void main(String[] args) {
        Main q = new Main();
        q.enque(10);
        q.enque(20);
        q.enque(30);
        q.enque(40);
        q.enque(50);

        q.deque();
        q.deque();
        q.deque();
        q.deque();
        q.deque();
    }
}