Compilare: user.cpp: In member function ‘bigint bigint::operator*(int) const’: user.cpp:31:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == res.z.size()) res.z.push_back(0); ^ user.cpp: In member function ‘bigint bigint::operator*(const bigint&) const’: user.cpp:42:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i + j + 1 > res.z.size()) res.z.push_back(0); ^ user.cpp: In function ‘int main()’: user.cpp:60:30: 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:61:35: 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); ^