Why pthread_condition variable getting hanged?

I just started learning pthread condition variable. But below code is not working as expected.

#include<iostream>
#include<pthread.h>

using namespace std;

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t count_threshold_cv = PTHREAD_COND_INITIALIZER;
int count=0;


void *inc_func(void *arg)
{
    pthread_mutex_lock(&mutex);
    int c;

    while(1)
    {
        cin>>c;
        if(c==8){ 
            pthread_cond_signal(&count_threshold_cv);break;}
    }

    cout<<"inc count reached 8"<<endl;
    pthread_mutex_unlock(&mutex);

}

void *watch(void *arg)
{
    pthread_mutex_lock(&mutex);
    while(1){
        pthread_cond_wait(&count_threshold_cv,&mutex);
        break;
    }
    cout<<"This executed"<<endl;
    pthread_mutex_unlock(&mutex);
}

int main()
{
    pthread_t id[26];
    pthread_create(&id[0],NULL,inc_func,NULL);
    pthread_create(&id[1],NULL,watch,NULL);

    int i;
    for(i=0;i<2;i++)
    {
        pthread_join(id[i],NULL);
    }

}

when the input is 8 this code gets hanged at "inc count reached 8? I am not able to understand. Where is my understanding wrong?