Compilare: user.cpp: In function ‘void insert(std::string)’: user.cpp:28:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) ^ user.cpp: In function ‘bool exist(unsigned int)’: user.cpp:35:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Hash[x % MOD].size(); ++i) ^