#include <thread>
#include <condition_variable>
#include <mutex>
#include <iostream>
#include <list>

std::mutex mtx;
std::condition_variable cv;

std::list<std::string> slowa;
thread_local std::string slowo;

void consumer(){
    while(true){
        {
            std::unique_lock<std::mutex> lock(mtx);
            cv.wait(lock, []{return slowa.size()!=0;});
            slowo = slowa.front();
            slowa.pop_front();
        }
        std::cout << slowo << std::endl;
    }
}

int main(){
    std::thread t(consumer);
    while(true) {
        std::cin >> slowo;
        {
            std::unique_lock<std::mutex> lock(mtx);
            slowa.push_back(slowo);
            cv.notify_one();
        }
    }
}