C++ Multithreading Calculate Fibonacci CHATGPT MAKE CODE

#include <iostream>
#include <thread>
#include <vector>

void fibonacci(int n, int& result) {
    if (n <= 1) {
        result = n;
    } else {
        int a, b;
        std::thread t1(fibonacci, n - 1, std::ref(a));
        std::thread t2(fibonacci, n - 2, std::ref(b));
        t1.join();
        t2.join();
        result = a + b;
    }
}

int main() {
    int n = 10; // Calculate Fibonacci sequence up to the 10th number
    int result;

    fibonacci(n, result);

    std::cout << "Fibonacci sequence up to " << n << "th number is: " << result << std::endl;

    return 0;
}