#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <fcntl.h>
#include <errno.h>


volatile int current_fd_ind = -1;
volatile int end = 0;
volatile int files_count = 0;


void handler1 (int signal) {
    end = 1;
}

void handler2 (int signal) {
    current_fd_ind = signal - SIGRTMIN;
}

int main(int argc, char *argv[]) {
    files_count = argc - 1;
    int pid  = getpid();
    int fds[20];
    long long sums[20];

    sigset_t sigset, empty;
    sigemptyset(&sigset);
    sigemptyset(&empty);
    sigaddset(&sigset, SIGTERM);
    for(int i = 0; i < argc - 1; i++) {
        sigaddset(&sigset, SIGRTMIN + i);
        sigaction(SIGRTMIN + i, &(struct sigaction) { .sa_handler = handler2, .sa_flags=0}, NULL);
        fds[i] = open(argv[i + 1], O_RDONLY);
        sums[i] = 0;
    }
    sigprocmask(SIG_BLOCK, &sigset, NULL);
    sigaction(SIGTERM, &(struct sigaction) { .sa_handler = handler1, .sa_flags=0}, NULL);

    printf("%d\n", pid);
    fflush(stdout);

    while(1) {
        if (!end && !(current_fd_ind != -1 && fds[current_fd_ind] != -1)) {
            sigsuspend(&empty);
        }
        if (end) {
            long long sum = 0;
            for(int i = 0; i < argc - 1; i++) {
                sum += sums[i];
                if (fds[i] != -1) {
                    close(fds[i]);
                }
            }
            printf("%lld\n", sum);
            fflush(stdout);
            exit(0);
        }
        while (current_fd_ind != -1 && fds[current_fd_ind] != -1 && !end) {
            errno = 0;
            char arg[17];
            sigprocmask(SIG_UNBLOCK, &sigset, NULL);
            int flag = read(fds[current_fd_ind], &arg, 16);
            sigprocmask(SIG_BLOCK, &sigset, NULL);
            if (flag == -1 && errno == EINTR) {
                continue;
            }
            if (flag == 0) {
                close(fds[current_fd_ind]);
                fds[current_fd_ind] = -1;
                current_fd_ind = -1;
            }
            if (flag == 16) {
                sums[current_fd_ind] += strtoll(arg, NULL, 10);
            }
        }
    }
    return 0;
}