#include <iostream>
#include <random>

int main() {
	std::random_device device;
	std::mt19937 generator(device());
    std::uniform_int_distribution<int> dist(0, 1);
    
	for (int i = 0, j = 0; i * j < 20; ++((dist(generator) == 1) ? i : j)) {
		std::cout << i << ", " << j << std::endl;
	}
	return 0;
}