Compilare: user.cpp: In function ‘int main()’: user.cpp:67:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<V[1].size();++i) ^ user.cpp:74:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<V[i].size();++j) ^ user.cpp:85:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<V[i-1].size();++j) ^ user.cpp:90:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<V[i].size();++j) ^ user.cpp:96:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<V[m].size();++i) ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:34:51: 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:12:47: 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); ^