Compilare: user.cpp: In function ‘std::vector<int> Merge(std::vector<int>, std::vector<int>)’: user.cpp:62:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < first.size() && j < second.size()) ^ user.cpp:62:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < first.size() && j < second.size()) ^ user.cpp:71:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < first.size()) { ^ user.cpp:75:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < second.size()) { ^ user.cpp: In function ‘void UpdateFenwick(std::vector<int>&, int)’: user.cpp:100:11: warning: statement has no effect [-Wunused-value] for (x; x < fenwick.size(); x += (x & -x)) ^ user.cpp:100:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (x; x < fenwick.size(); x += (x & -x)) ^ user.cpp: In function ‘int QueryFenwick(const std::vector<int>&, int)’: user.cpp:108:11: warning: statement has no effect [-Wunused-value] for (x; x > 0; x -= (x & -x)) ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:36:51: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:14:47: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, SIZE, 1, input_file); ^