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

int balance = 0;
pthread_mutex_t mon = PTHREAD_MUTEX_INITIALIZER;

void deposit(int n) {
    pthread_mutex_lock(&mon);
    balance += n;
    pthread_mutex_unlock(&mon);
}

void *worker(void *arg) { (void)arg;
    for (int i = 0; i < 1000; i++)
        deposit(1);
    return NULL;
}

int main(void) {
    pthread_t t1, t2;
    pthread_create(&t1, NULL, worker, NULL);
    pthread_create(&t2, NULL, worker, NULL);
    pthread_join(t1, NULL);
    pthread_join(t2, NULL);
    printf("%d\n", balance);
    return 0;
}