Compilare: user.cpp: In function ‘void euler(int, int)’: user.cpp:18:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s.size() != size) ^ user.cpp: In function ‘int main()’: user.cpp:62:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biti.in", "r", stdin); ^ user.cpp:63:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biti.out", "w", stdout); ^