Compilare: user.cpp: In function ‘void Z(std::string, int*)’: user.cpp:27:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1 ; i < S.size() ; ++i) { ^ user.cpp:30:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (r < S.size() && S[r] == S[r - l]) ^ user.cpp:42:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (r < S.size() && S[r] == S[r - l]) ++r; ^