Compilare: user.cpp: In function ‘void multiply(std::vector<int>&, std::vector<int>&)’: user.cpp:66:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i(0); i < a.size(); i++) ~~^~~~~~~~~~ user.cpp:68:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i(0); i < b.size(); i++) ~~^~~~~~~~~~ user.cpp:82:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (a.size() > m && a.back() == 0) ~~~~~~~~~^~~ user.cpp: In function ‘int main()’: user.cpp:151:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i(nrbiti * a.size() - 1); i < nrbiti * b.size(); i += nrbiti) ~~^~~~~~~~~~~~~~~~~~~