Compilare: user.cpp: In member function ‘bigint bigint::operator*(int) const’: user.cpp:24:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == res.z.size()) res.z.push_back(0); ^ user.cpp: In function ‘int main()’: user.cpp:42:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm.in","r",stdin); ^ user.cpp:43:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm.out","w",stdout); ^