#include <stdio.h>
#include <stdlib.h>

#define MAX_CAPACITY 5

// Define the queue structure
typedef struct {
    int data[MAX_CAPACITY];
    int front;
    int rear;
    int size;
} Queue;

// Initialize the queue
void initQueue(Queue *q) {
    q->front = 0;
    q->rear = -1;
    q->size = 0;
}

// Returns the current size of the queue
int size(Queue *q) {
    return q->size;
}

// Pushes two values into the queue
void Push(Queue *q, int val1, int val2) {
    if (q->size + 2 <= MAX_CAPACITY) {
        q->rear = (q->rear + 1) % MAX_CAPACITY;
        q->data[q->rear] = val1;
        q->size++;

        q->rear = (q->rear + 1) % MAX_CAPACITY;
        q->data[q->rear] = val2;
        q->size++;
    } else {
        printf("Overflow\n");
    }
}

// Pops the front two elements and pushes their absolute difference
void pop(Queue *q) {
    if (q->size < 2) {
        printf("Underflow\n");
    } else {
        int val1 = q->data[q->front];
        q->front = (q->front + 1) % MAX_CAPACITY;
        q->size--;

        int val2 = q->data[q->front];
        q->front = (q->front + 1) % MAX_CAPACITY;
        q->size--;

        int diff = abs(val1 - val2);
        if (q->size < MAX_CAPACITY) {
            q->rear = (q->rear + 1) % MAX_CAPACITY;
            q->data[q->rear] = diff;
            q->size++;
        } else {
            printf("Overflow\n");
        }
    }
}

// Returns the front element of the queue
int front(Queue *q) {
    if (q->size > 0) {
        return q->data[q->front];
    } else {
        return -1; // Queue is empty
    }
}

// Returns the back element of the queue
int back(Queue *q) {
    if (q->size > 0) {
        return q->data[q->rear];
    } else {
        return -1; // Queue is empty
    }
}

// Main function to demonstrate the queue operations
int main() {
    Queue q;
    initQueue(&q);

    // Demonstrate functionalities
    Push(&q, 3, 5);
    printf("Front: %d\n", front(&q));
    printf("Back: %d\n", back(&q));
    printf("Size: %d\n", size(&q));

    Push(&q, 8, 2);
    printf("Front: %d\n", front(&q));
    printf("Back: %d\n", back(&q));
    printf("Size: %d\n", size(&q));

    pop(&q);
    printf("After pop\n");
    printf("Front: %d\n", front(&q));
    printf("Back: %d\n", back(&q));
    printf("Size: %d\n", size(&q));

    Push(&q, 7, 1);
    printf("After pushing more elements\n");
    printf("Front: %d\n", front(&q));
    printf("Back: %d\n", back(&q));
    printf("Size: %d\n", size(&q));

    return 0;
}