#include <iostream>
#include <future>
#include <chrono>
#include <condition_variable>
#include <iostream>
#include <mutex>
#include <string>
#include <thread>

using namespace std ;

int calculate_value()
{
    cout << "Calculating value in background...\n";
    this_thread::sleep_for(chrono::seconds(20)); // Simulate long computation
    return 42;
}

int main()
{
    future<int> future_result = async(launch::async, calculate_value);

    cout << "Main thread continues to execute. Waits for 10 seconds\n";
    this_thread::sleep_for(chrono::seconds(10));
    cout << "Waiting for result...\n";
    future_result.wait(); // Blocks until the result is available

    cout << "function call completed. "  << endl;

    return 0;
}