#include <stdio.h>
#define MAX_SIZE 100
#define NUM_STACKS 3

int tops[NUM_STACKS] = {-1, -1, -1};
int stack[MAX_SIZE];
int stack_size = MAX_SIZE / NUM_STACKS;

void push(int stack_num, int value) {
    int index = stack_num * stack_size + tops[stack_num] + 1;
    if (tops[stack_num] < stack_size - 1) {
        tops[stack_num]++;
        stack[index] = value;
        printf("Pushed %d to stack %d\n", value, stack_num);
    } else {
        printf("Stack %d is full\n", stack_num);
    }
}

int pop(int stack_num) {
    int index = stack_num * stack_size + tops[stack_num];
    if (tops[stack_num] >= 0) {
        int value = stack[index];
        tops[stack_num]--;
        printf("Popped %d from stack %d\n", value, stack_num);
        return value;
    } else {
        printf("Stack %d is empty\n", stack_num);
        return -1;
    }
}

int main() {
    push(0, 10);
    push(0, 20);
    push(1, 30);
    push(2, 40);

    pop(0);
    pop(1);
    pop(2);
    pop(2);

    return 0;
}