I am trying to learn process synchronization , I am trying semaphore,

My code snippet is as below:

#include <semaphore.h>
#include <unistd.h>
#include <iostream>
#include <thread>
using namespace std;

sem_t s,s1;

void odd(int& value)
{
    while (value<10)
    {
        if(sem_wait(&s) == 0)
        {
            cout << "odd thread: " <<" process id: "<< getpid() <<" thread id: "<< this_thread::get_id()<<" value: "<<value<<'\n';
            value++;
            sem_post(&s1);
        }
    }
}

void even(int& value)
{
    while (value < 11)
    {
        if(sem_wait(&s1) == 0)
        {
            cout << "even thread: " <<" process id: "<< getpid() <<" thread id: "<< this_thread::get_id()<<" value: "<<value<<'\n';
            value++;
            sem_post(&s);
        }
    }
}

int main()
{

    int value = 1;
    //sem_t s,s1;
    sem_init(&s,0,1);
    sem_init(&s1,0,0);
    
    pid_t pid = fork();
    
    if(pid < 0)
        cout<<"Fork failedn";
    else
    {
        if(pid)
        {
            cout<<"Parent process creating odd thread, parent process id: "<<getpid()<<'n';
            odd(value);
        }
        else
        {
            cout<<"Child process creating even thread, child process id: "<<getpid()<<'n';
            even(value);
        }
    }
    return EXIT_SUCCESS;
}

Only the parent process is able to execute odd function , Even function is not getting executed, sorry for asking a very basic question , but since I am beginner to C++ , I am facing this problem , please suggest if I am doing something wrong.

I was expecting that the parent and child process should be able to execute the respective odd and even functions