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

static bool value_set;
static int value;

// Set the value to the integer pointed to by args
static void* ValueSetter(void* args) {
  int value_to_set = *(int*) args;
  if (!value_set) {
    value = value_to_set;
    value_set = true;
  }
  return NULL;
}

int main(int argc, char* argv[]) {
  value_set = false;
  pthread_t p1, p2;
  int p1_value = 10;
  int p2_value = 20;
  pthread_attr_t pthread_attributes;
  pthread_attr_init(&pthread_attributes);
  pthread_attr_setdetachstate(&pthread_attributes, PTHREAD_CREATE_JOINABLE);
  if (pthread_create(&p1, NULL, &ValueSetter, &p1_value) != 0 ||
      pthread_create(&p2, NULL, &ValueSetter, &p2_value) != 0) {
    perror("Creating a thread failed");
    return 1;
  }
  pthread_attr_destroy(&pthread_attributes);

  void* return_value;
  if (pthread_join(p1, &return_value) != 0 ||
      pthread_join(p2, &return_value) != 0) {
    perror("Joining with a thread failed");
    return 1;
  }

  printf("Value is %d\n", value);

  return 0;
}