I don't know why (-1 < s.size()) evaluates to false, when -1 is less than 3.

Code:
int main()
{
	string s = "abc";
	
	cout << s.size() << '\n';

	if (-1 < s.size()) {
		cout << "yes";
	} else {
		cout << "no";
	}

	keep_window_open();
}