Compilare: user.cpp: In function ‘void operator+=(big&, big)’: user.cpp:76:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (a.d.size() == i) a.d.push_back(0); ^ user.cpp: In function ‘int main()’: user.cpp:104:27: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘__gnu_cxx::__alloc_traits<std::allocator<long long int> >::value_type {aka long long int}’ [-Wformat=] printf("%d",ans.d[len]); ^ user.cpp:105:50: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘__gnu_cxx::__alloc_traits<std::allocator<long long int> >::value_type {aka long long int}’ [-Wformat=] while (-- len >= 0) printf("%018d",ans.d[len]); ^ user.cpp:89:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pm.out","w",stdout); ^