Compilare: user.cpp: In function ‘void sieve()’: user.cpp:52:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < primes.size() && primes[j] <= low[i] && i * primes[j] < NMAX; ++ j) ^ user.cpp: In function ‘void process()’: user.cpp:94:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < cycle.size(); ++ i) { ^ user.cpp:110:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < cycle.size(); ++ i) ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:14:43: 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 member function ‘void InputReader::advance()’: user.cpp:36:47: 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); ^