#include <iostream>
#include <sstream>
#include <stdint.h>

std::string bitwiseOne(const std::string& a, const std::string& b) {

	std::string out;

	for (size_t i = 0; i < a.size(); ++i) {
		if (a[i] == '1' || b[i] == '1') {
			out +=  '1';
		} else {
			out += '0';
		}
	}

	return out;
}

int main(int argc, char** argv) {

	std::string a = "1001";
	std::string b = "0100";
	std::cout << bitwiseOne(a, b) << std::endl;
	return 0;
}