#include <pthread.h>
#include <stdio.h>

pthread_mutex_t lock;
int             counter = 0;

void *worker(void *arg) {
    printf("Hello from %s!\n", (char *)arg);
    for (int i = 0; i < 100000; i++) {
        pthread_mutex_lock(&lock);
        counter++;
        pthread_mutex_unlock(&lock);
    }
    return NULL;
}

int main() {
    pthread_t thread1, thread2;

    pthread_mutex_init(&lock, NULL);

    pthread_create(&thread1, NULL, worker, "Thread1");
    pthread_create(&thread2, NULL, worker, "Thread2");

    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL);

    pthread_mutex_destroy(&lock);

    printf("Counter value: %d\n", counter);
    return 0;
}