#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <signal.h>

enum { COUNT = 4 };
enum { SIMPL = 2 };

volatile int cnt = 0;
int sim = 0;

void hand_SIGTERM(int sig) {
    _exit(0);
}
void hand_SIGINT(int sig) {
    signal(SIGINT, hand_SIGINT);
    if (++cnt == COUNT) {
        _exit(0);
    }
    printf("%d\n", sim);
}

int simpl_check(int val) {
    if (val < 0) {
        return 0;
    }
    for (unsigned long long i = SIMPL; i * i <= val; ++i) {
        if (!(val % i)) {
            return 0;
        }
    }
    return 1;
}

int main(int argc, char **argv) {

    long long low, high;
    scanf("%lld", &low);
    scanf("%lld", &high);

    printf("%d\n", getpid());

    signal(SIGTERM, hand_SIGTERM);
    signal(SIGINT, hand_SIGINT);

    for (unsigned long long i = low; i < high; ++i) {
        if (simpl_check(i)) {
            sim = i;
        }
    }
    printf("-1\n");
    _exit(0);
}