#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <sys/shm.h>
#include <sys/sem.h>
#define u unsigned
int semid, maxval, nproc;
int* memory;

int proc(int i){
    while (semop(semid, (struct sembuf[]){{i, -1, 0}}, 1) >= 0){
        int a = memory[0];
        printf("%d: %d\n", i, a);
        fflush(stdout);
        a++;
        if (a > maxval){
            semctl(semid, 0, IPC_RMID, (int) 0);
            return 0;
        }
        memory[0] = a;
        int next = (a * a) % nproc;
        semop(semid, (struct sembuf[]){{next, 1, 0}}, 1);
    }
    return 0;
}

int main(int argc, char** argv){
    nproc = strtol(argv[1], NULL, 10);
    key_t key = strtol(argv[2], NULL, 10);
    maxval = strtol(argv[3], NULL, 10);

    int shmid = shmget(key, sizeof(int), 0600 | IPC_CREAT);
    memory = shmat(shmid, NULL, 0);
    memory[0] = 0;

    semid = semget(key, nproc, 0600 | IPC_CREAT);
    semctl(semid, nproc, SETALL, (int) 0);
    struct sembuf cmd[] = {{0, 1, 0}};
    semop(semid, (struct sembuf[]){{0, 1, 0}}, 1);

    for (int i = 0; i < nproc; ++i){
        if (!fork()){
            proc(i);
            exit(0);
        }
    }
    while (wait(NULL) != -1);
    shmctl(shmid, IPC_RMID, NULL);
    return 0;
}