Compilare: main.cpp: In function 'void find_substr(std::__cxx11::string, int (&)[2000009])': main.cpp:12:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < s.length(); ++ i) ~~^~~~~~~~~~~~ main.cpp:19:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (r < s.length() && s[r] == s[r - i]) ~~^~~~~~~~~~~~