#include <stdio.h>

int front = 0;
int rear = 0;

void enqueue() {
    rear = (rear + 1) % 5;
}

void dequeue() {
    front = (front + 1) % 5;
}

int main() {
    enqueue(10); 
    enqueue(20); 
    enqueue(30); 
    dequeue();
    enqueue(40); 

    printf("front: %d\n", front);
    printf("rear: %d\n", rear);

    return 0;
}