#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <signal.h>

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

    int shmid = shmget(key, sizeof(int), 0600 | IPC_CREAT);
    int *shm = (int *) shmat(shmid, (void*)0, 0);

    int semid = semget(key, nproc, 0600 | IPC_CREAT);
    semctl(semid, nproc, SETALL, (int) 0);
    semctl(semid, 0, SETVAL, 1);
    *shm = 0;

    for (int i = 0; i < nproc; i++) {
        if (!(pids[i] = fork())) {
            while(1) {
                struct sembuf ops[1] =
                {
                    { .sem_num = i, .sem_op = -1, .sem_flg = 0 },
                };
                semop(semid, ops, 1);
                int val = *shm + 1;
                printf("%d %d\n", i, val - 1);
                fflush(stdin);
                *shm += 1;
                if (val > maxval - 1) {
                    exit(0);
                }
                ops[0].sem_op = 1;
                ops[0].sem_num = (val * val) % nproc;
                semop(semid, ops, 1);
            }
        }
    }
    wait(NULL);
    shmdt(shm);
    semctl(semid, nproc, IPC_RMID);
    shmctl(shmid, IPC_RMID, NULL);
    for (int i = 1; i < nproc; i++) {
        kill(pids[i], SIGKILL);
    }
    while (wait(NULL) > 0) {
    }
}