Pudges exercise in C++

main.cpp

#include <iostream>
#include <string>

int main(int argc, char *argv[]) {
	for (int i=1000; i<10000; i++) {
		std::string s = std::to_string(i);
		int sum = std::stoi(s.substr(0, 2)) + std::stoi(s.substr(2, 2));
		if (sum * sum == i) {
			std::cout << i << "\n";
		}
	}
	return 0;
}